Image processing apparatus and method, and image pickup apparatus

ABSTRACT

An object of the present invention is to make it possible to specify a background image area, a moving object image area, and an image area in which the mixture of the background image area and the moving object image area occurs. A mixture-ratio calculator  103  extracts pixel data of a peripheral frame corresponding to a designated pixel of a designated frame of the image data as background pixel data corresponding to a background object, and also extracts designated pixel data of the designated pixel contained in the designated frame so as to generate a plurality of relational expressions indicating the relationship between the designated pixel data and the background pixel data. The mixture-ratio calculator  103  detects the mixture ratio indicating the mixture state of the objects based on the relational expressions. An area specifying unit  104  calculates a predictive error by substituting the detected mixture ratio into the relational expressions, and determines whether an area to which the designated pixel belongs is a covered background area, an uncovered background area, a foreground area, or a background area. The present invention is applicable to an image processing apparatus.

TECHNICAL FIELD

[0001] The present invention relates to image processing apparatuses andmethods, and image-capturing apparatuses, and more particularly, to animage processing apparatus and method, and an image-capturing apparatusin which a difference between a signal detected by a sensor and the realworld is taken into consideration.

BACKGROUND ART

[0002] A technique for detecting incidents occurring in the real worldby a sensor and for processing sampled data output from the image sensoris widely used.

[0003] For example, motion blur occurs in an image obtained by capturingan object moving in front of a predetermined stationary background witha video camera if the moving speed is relatively high.

[0004] However, when an object is moving in front of a stationarybackground, not only does motion blur caused by the mixture of themoving object itself occur, but also the mixture of the background imageand the moving object image occurs. Hitherto, the processing for dealingwith the mixture state of the background image and the moving object hasnot been considered.

DISCLOSURE OF INVENTION

[0005] The present invention has been made in view of theabove-described background. Accordingly, it is an object of the presentinvention to make it possible to specify a background image area, amoving object area, and an image area in which the mixture of thebackground image area and the moving object area occurs.

[0006] An image processing apparatus of the present invention includes:relational-expression generating means for extracting, in correspondencewith a designated pixel of a designated frame of image data, pixel dataof a peripheral frame around the designated frame as background pixeldata corresponding to a background object which forms a background amonga plurality of objects of the image data, and also for extractingdesignated pixel data of the designated pixel contained in thedesignated frame so as to generate a plurality of relational expressionsconcerning the designated pixel indicating the relationship between thedesignated pixel data and the background pixel data; mixture-ratiodetection means for detecting a mixture ratio indicating the mixturestate of the plurality of objects in the real world concerning thedesignated pixel based on the relational expressions; predictive-errorcalculation means for calculating a predictive error by substituting themixture ratio detected by the mixture-ratio detection means into therelational expressions; covered background area/uncovered backgroundarea specifying means for specifying, based on the predictive error,whether an area to which the designated pixel belongs is a mixed area inwhich the plurality of objects are mixed and is also a coveredbackground area formed at a leading end in the moving direction of aforeground object which forms a foreground among the plurality ofobjects, or is the mixed area and is also an uncovered background areaformed at a trailing end in the moving direction of the foregroundobject; and foreground area/background area specifying means forspecifying whether the area to which the designated pixel belongs is aforeground area consisting of only foreground object components whichform the foreground object or a background area consisting of onlybackground object components which form the background object.

[0007] The mixture-ratio detection means may detect the foregroundobject components contained in the designated pixel in correspondencewith the designated pixel based on the relational expressions, and mayalso detect the mixture ratio; and the predictive-error calculationmeans may calculate the predictive error by substituting the mixtureratio and the foreground object components contained in the designatedpixel detected by the mixture-ratio detection means into the relationalexpressions.

[0008] The relational-expression generating means may extract the pixeldata of the peripheral frame corresponding to the designated pixel asthe background pixel data corresponding to the background object, andmay also extract the designated pixel data of the designated pixel andvicinity pixel data of a vicinity pixel positioned in the vicinity ofthe designated pixel in the designated frame, and may generate theplurality of relational expressions concerning the designated pixelindicating the relationship among the designated pixel data, thevicinity pixel data, and the background pixel data corresponding to thedesignated pixel data or the vicinity pixel data.

[0009] The relational-expression generating means may generate theplurality of relational expressions based on a first approximation inwhich the foreground object components contained in the designated pixeldata and the vicinity pixel data are equal, and a second approximationin which the mixture ratio in the mixed area linearly changes withrespect to the position of the pixel of the mixed area.

[0010] The relational-expression generating means may generate theplurality of relational expressions based on a first approximation inwhich the foreground object components contained in the designated pixeldata and the vicinity pixel data are equal, and a second approximationin which the mixture ratio in the mixed area planarly changes withrespect to the position of the pixel of the mixed area.

[0011] The mixture-ratio detection means may detect the mixture ratio bysolving the plurality of relational expressions according to the methodof least squares.

[0012] The relational-expression generating means may generate theplurality of relational expressions by extracting the pixel data of theframe prior to the designated frame as the background pixel data whenthe designated pixel belongs to the covered background area and byextracting the pixel data of the frame subsequent to the designatedframe as the background pixel data when the designated pixel belongs tothe uncovered background area.

[0013] The relational-expression generating means may generate theplurality of relational expressions by extracting, in correspondencewith the designated pixel, mixed pixel data indicating the mixture statein which the plurality of objects are mixed from the designated frameand the peripheral frame based on the motion of the foreground objectand by also extracting, in correspondence with each item of the mixedpixel data, the background pixel data corresponding to the backgroundobject from a frame different from the frame from which the mixed pixeldata is extracted based on the motion of the background object.

[0014] The relational-expression generating means may generate theplurality of relational expressions based on a first approximation inwhich the foreground object components corresponding to the mixed pixeldata are equal and a second approximation in which the mixed pixel dataextracted from the designated frame and the peripheral frame areuniform.

[0015] The relational-expression generating means may generate theplurality of relational expressions by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and by also extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame prior to the frame from which the mixedpixel data is extracted based on the motion of the background object.The covered background area/uncovered background area specifying meansmay specify an area in which the predictive error is greater than orequal to a predetermined threshold as the uncovered background area.

[0016] The relational-expression generating means may generate theplurality of relational expressions by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and also by extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame subsequent to the frame from which themixed pixel data is extracted based on the motion of the backgroundobject. The covered background area/uncovered background area specifyingmeans may specify an area in which the predictive error is greater thanor equal to a predetermined threshold as the covered background area.

[0017] An image processing method includes: a relational-expressiongenerating step of extracting, in correspondence with a designated pixelof a designated frame of image data, pixel data of a peripheral framearound the designated frame as background pixel data corresponding to abackground object which forms a background among a plurality of objectsof the image data, and also of extracting designated pixel data of thedesignated pixel contained in the designated frame so as to generate aplurality of relational expressions concerning the designated pixelindicating the relationship between the designated pixel data and thebackground pixel data; a mixture-ratio detection step of detecting amixture ratio indicating the mixture state of the plurality of objectsin the real world concerning the designated pixel based on therelational expressions; a predictive-error calculation step ofcalculating a predictive error by substituting the mixture ratiodetected by the processing in the mixture-ratio detection step into therelational expressions; a covered background area/uncovered backgroundarea specifying step of specifying, based on the predictive error,whether an area to which the designated pixel belongs is a mixed area inwhich the plurality of objects are mixed and is also a coveredbackground area formed at a leading end in a moving direction of aforeground object which forms a foreground among the plurality ofobjects, or is the mixed area and is also an uncovered background areaformed at a trailing end in the moving direction of the foregroundobject; and a foreground area/background area specifying step ofspecifying whether the area to which the designated pixel belongs is aforeground area consisting of only foreground object components whichform the foreground object or a background area consisting of onlybackground object components which form the background object.

[0018] In the mixture-ratio detection step, the foreground objectcomponents contained in the designated pixel may be detected incorrespondence with the designated pixel based on the relationalexpressions, and the mixture ratio may also be detected. In thepredictive-error calculation step, the predictive error may becalculated by substituting the mixture ratio and the foreground objectcomponents contained in the designated pixel detected by the processingin the mixture-ratio detection step into the relational expressions.

[0019] In the relational-expression generating step, the pixel data ofthe peripheral frame corresponding to the designated pixel may beextracted as the background pixel data corresponding to the backgroundobject, and the designated pixel data of the designated pixel andvicinity pixel data of a vicinity pixel positioned in the vicinity ofthe designated pixel in the designated frame may also be extracted, andthe plurality of relational expressions concerning the designated pixelindicating the relationship among the designated pixel data, thevicinity pixel data, and the background pixel data corresponding to thedesignated pixel data or the vicinity pixel data.

[0020] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components contained in the designatedpixel data and the vicinity pixel data are equal, and a secondapproximation in which the mixture ratio in the mixed area linearlychanges with respect to the position of the pixel of the mixed area.

[0021] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components contained in the designatedpixel data and the vicinity pixel data are equal, and a secondapproximation in which the mixture ratio in the mixed area planarlychanges with respect to the position of the pixel of the mixed area.

[0022] In the mixture-ratio detection step, the mixture ratio may bedetected by solving the plurality of relational expressions according tothe method of least squares.

[0023] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting the pixel data ofthe frame prior to the designated frame as the background pixel datawhen the designated pixel belongs to the covered background area and byextracting the pixel data of the frame subsequent to the designatedframe as the background pixel data when the designated pixel belongs tothe uncovered background area.

[0024] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, mixed pixel data indicating the mixture statein which the plurality of objects are mixed from the designated frameand the peripheral frame based on the motion of the foreground objectand by also extracting, in correspondence with each item of the mixedpixel data, the background pixel data corresponding to the backgroundobject from a frame different from the frame from which the mixed pixeldata is extracted based on the motion of the background object.

[0025] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components corresponding to the mixedpixel data are equal and a second approximation in which the mixed pixeldata extracted from the designated frame and the peripheral frame areuniform.

[0026] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and by also extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame prior to the frame from which the mixedpixel data is extracted based on the motion of the background object. Inthe covered background area/uncovered background area specifying step,an area in which the predictive error is greater than or equal to apredetermined threshold is specified as the uncovered background area.

[0027] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and also by extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame subsequent to the frame from which themixed pixel data is extracted based on the motion of the backgroundobject. In the covered background area/uncovered background areaspecifying step, an area in which the predictive error is greater thanor equal to a predetermined threshold may be specified as the coveredbackground area.

[0028] A program of a recording medium of the present inventionincludes: a relational-expression generating step of extracting, incorrespondence with a designated pixel of a designated frame of imagedata, pixel data of a peripheral frame around the designated frame asbackground pixel data corresponding to a background object which forms abackground among a plurality of objects of the image data, and also ofextracting designated pixel data of the designated pixel contained inthe designated frame so as to generate a plurality of relationalexpressions concerning the designated pixel indicating the relationshipbetween the designated pixel data and the background pixel data; amixture-ratio detection step of detecting a mixture ratio indicating themixture state of the plurality of objects in the real world concerningthe designated pixel based on the relational expressions; apredictive-error calculation step of calculating a predictive error bysubstituting the mixture ratio detected by the processing in themixture-ratio detection step into the relational expressions; a coveredbackground area/uncovered background area specifying step of specifying,based on the predictive error, whether an area to which the designatedpixel belongs is a mixed area in which the plurality of objects aremixed and is also a covered background area formed at a leading end in amoving direction of a foreground object which forms a foreground amongthe plurality of objects, or is the mixed area and is also an uncoveredbackground area formed at a trailing end in the moving direction of theforeground object; and a foreground area/background area specifying stepof specifying whether the area to which the designated pixel belongs isa foreground area consisting of only foreground object components whichform the foreground object or a background area consisting of onlybackground object components which form the background object.

[0029] In the mixture-ratio detection step, the foreground objectcomponents contained in the designated pixel may be detected incorrespondence with the designated pixel based on the relationalexpressions, and the mixture ratio may also be detected. In thepredictive-error calculation step, the predictive error may becalculated by substituting the mixture ratio and the foreground objectcomponents contained in the designated pixel detected by the processingin the mixture-ratio detection step into the relational expressions.

[0030] In the relational-expression generating step, the pixel data ofthe peripheral frame corresponding to the designated pixel may beextracted as the background pixel data corresponding to the backgroundobject, and the designated pixel data of the designated pixel andvicinity pixel data of a vicinity pixel positioned in the vicinity ofthe designated pixel in the designated frame may also be extracted, andthe plurality of relational expressions concerning the designated pixelindicating the relationship among the designated pixel data, thevicinity pixel data, and the background pixel data corresponding to thedesignated pixel data or the vicinity pixel data.

[0031] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components contained in the designatedpixel data and the vicinity pixel data are equal, and a secondapproximation in which the mixture ratio in the mixed area linearlychanges with respect to the position of the pixel of the mixed area.

[0032] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components contained in the designatedpixel data and the vicinity pixel data are equal, and a secondapproximation in which the mixture ratio in the mixed area planarlychanges with respect to the position of the pixel of the mixed area.

[0033] In the mixture-ratio detection step, the mixture ratio may bedetected by solving the plurality of relational expressions according tothe method of least squares.

[0034] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting the pixel data ofthe frame prior to the designated frame as the background pixel datawhen the designated pixel belongs to the covered background area and byextracting the pixel data of the frame subsequent to the designatedframe as the background pixel data when the designated pixel belongs tothe uncovered background area.

[0035] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, mixed pixel data indicating a mixture statein which the plurality of objects are mixed from the designated frameand the peripheral frame based on the motion of the foreground objectand by also extracting, in correspondence with each item of the mixedpixel data, the background pixel data corresponding to the backgroundobject from a frame different from the frame from which the mixed pixeldata is extracted based on the motion of the background object.

[0036] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components corresponding to the mixedpixel data are equal and a second approximation in which the mixed pixeldata extracted from the designated frame and the peripheral frame areuniform.

[0037] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and by also extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame prior to the frame from which the mixedpixel data is extracted based on the motion of the background object. Inthe covered background area/uncovered background area specifying step,an area in which the predictive error is greater than or equal to apredetermined threshold may be specified as the uncovered backgroundarea.

[0038] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and also by extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame subsequent to the frame from which themixed pixel data is extracted based on the motion of the backgroundobject. In the covered background area/uncovered background areaspecifying step, an area in which the predictive error is greater thanor equal to a predetermined threshold may be specified as the coveredbackground area.

[0039] A program of the present invention allows a computer to execute:a relational-expression generating step of extracting, in correspondencewith a designated pixel of a designated frame of image data, pixel dataof a peripheral frame around the designated frame as background pixeldata corresponding to a background object which forms a background amonga plurality of objects of the image data, and also of extractingdesignated pixel data of the designated pixel contained in thedesignated frame so as to generate a plurality of relational expressionsconcerning the designated pixel indicating the relationship between thedesignated pixel data and the background pixel data; a mixture-ratiodetection step of detecting a mixture ratio indicating the mixture stateof the plurality of objects in the real world concerning the designatedpixel based on the relational expressions; a predictive-errorcalculation step of calculating a predictive error by substituting themixture ratio detected by the processing in the mixture-ratio detectionstep into the relational expressions; a covered backgroundarea/uncovered background area specifying step of specifying, based onthe predictive error, whether an area to which the designated pixelbelongs is a mixed area in which the plurality of objects are mixed andis also a covered background area formed at a leading end in a movingdirection of a foreground object which forms a foreground among theplurality of objects, or is the mixed area and is also an uncoveredbackground area formed at a trailing end in the moving direction of theforeground object; and a foreground area/background area specifying stepof specifying whether the area to which the designated pixel belongs isa foreground area consisting of only foreground object components whichform the foreground object or a background area consisting of onlybackground object components which form the background object.

[0040] In the mixture-ratio detection step, the foreground objectcomponents contained in the designated pixel may be detected incorrespondence with the designated pixel based on the relationalexpressions, and the mixture ratio may also be detected. In thepredictive-error calculation step, the predictive error may becalculated by substituting the mixture ratio and the foreground objectcomponents contained in the designated pixel detected by the processingin the mixture-ratio detection step into the relational expressions.

[0041] In the relational-expression generating step, the pixel data ofthe peripheral frame corresponding to the designated pixel may beextracted as the background pixel data corresponding to the backgroundobject, and the designated pixel data of the designated pixel andvicinity pixel data of a vicinity pixel positioned in the vicinity ofthe designated pixel in the designated frame may also be extracted, andthe plurality of relational expressions concerning the designated pixelindicating the relationship among the designated pixel data, thevicinity pixel data, and the background pixel data corresponding to thedesignated pixel data or the vicinity pixel data.

[0042] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components contained in the designatedpixel data and the vicinity pixel data are equal, and a secondapproximation in which the mixture ratio in the mixed area linearlychanges with respect to the position of the pixel of the mixed area.

[0043] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components contained in the designatedpixel data and the vicinity pixel data are equal, and a secondapproximation in which the mixture ratio in the mixed area planarlychanges with respect to the position of the pixel of the mixed area.

[0044] In the mixture-ratio detection step, the mixture ratio may bedetected by solving the plurality of relational expressions according tothe method of least squares.

[0045] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting the pixel data ofthe frame prior to the designated frame as the background pixel datawhen the designated pixel belongs to the covered background area and byextracting the pixel data of the frame subsequent to the designatedframe as the background pixel data when the designated pixel belongs tothe uncovered background area.

[0046] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, mixed pixel data indicating a mixture statein which the plurality of objects are mixed from the designated frameand the peripheral frame based on the motion of the foreground objectand by also extracting, in correspondence with each item of the mixedpixel data, the background pixel data corresponding to the backgroundobject from a frame different from the frame from which the mixed pixeldata is extracted based on the motion of the background object.

[0047] In the relational-expression generating step, the plurality ofrelational expressions may be generated based on a first approximationin which the foreground object components corresponding to the mixedpixel data are equal and a second approximation in which the mixed pixeldata extracted from the designated frame and the peripheral frame areuniform.

[0048] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and by also extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame prior to the frame from which the mixedpixel data is extracted based on the motion of the background object. Inthe covered background area/uncovered background area specifying step,an area in which the predictive error is greater than or equal to apredetermined threshold may be specified as the uncovered backgroundarea.

[0049] In the relational-expression generating step, the plurality ofrelational expressions may be generated by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and also by extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame subsequent to the frame from which themixed pixel data is extracted based on the motion of the backgroundobject. In the covered background area/uncovered background areaspecifying step, an area in which the predictive error is greater thanor equal to a predetermined threshold may be specified as the coveredbackground area.

[0050] An image-capturing apparatus of the present invention includes:image-capturing means for outputting a subject image captured by animage-capturing device including a predetermined number of pixels, thepixels having a time integrating function, as image data formed of apredetermined number of pixel data; relational-expression generatingmeans for extracting, in correspondence with a designated pixel of adesignated frame of the image data, the pixel data of a peripheral framearound the designated frame as background pixel data corresponding to abackground object which forms a background among a plurality of objectsof the image data, and also for extracting designated pixel data of thedesignated pixel contained in the designated frame so as to generate aplurality of relational expressions concerning the designated pixelindicating a relationship between the designated pixel data and thebackground pixel data; mixture-ratio detection means for detecting amixture ratio indicating the mixture state of the plurality of objectsin the real world concerning the designated pixel based on therelational expressions; predictive-error calculation means forcalculating a predictive error by substituting the mixture ratiodetected by the mixture-ratio detection means into the relationalexpressions; covered background area/uncovered background areaspecifying means for specifying, based on the predictive error, whetheran area to which the designated pixel belongs is a mixed area in whichthe plurality of objects are mixed and is also a covered background areaformed at a leading end in a moving direction of a foreground objectwhich forms a foreground among the plurality of objects, or is the mixedarea and is also an uncovered background area formed at a trailing endin the moving direction of the foreground object; and foregroundarea/background area specifying means for specifying whether the area towhich the designated pixel belongs is a foreground area consisting ofonly foreground object components which form the foreground object or abackground area consisting of only background object components whichform the background object.

[0051] The mixture-ratio detection means may detect the foregroundobject components contained in the designated pixel in correspondencewith the designated pixel based on the relational expressions, and mayalso detect the mixture ratio. The predictive-error calculation meansmay calculate the predictive error by substituting the mixture ratio andthe foreground object components contained in the designated pixeldetected by the mixture-ratio detection means into the relationalexpressions.

[0052] The relational-expression generating means may extract the pixeldata of the peripheral frame corresponding to the designated pixel asthe background pixel data corresponding to the background object, andmay also extract the designated pixel data of the designated pixel andvicinity pixel data of a vicinity pixel positioned in the vicinity ofthe designated pixel in the designated frame, and may generate theplurality of relational expressions concerning the designated pixelindicating the relationship among the designated pixel data, thevicinity pixel data, and the background pixel data corresponding to thedesignated pixel data or the vicinity pixel data.

[0053] The relational-expression generating means may generate theplurality of relational expressions based on a first approximation inwhich the foreground object components contained in the designated pixeldata and the vicinity pixel data are equal, and a second approximationin which the mixture ratio in the mixed area linearly changes withrespect to the position of the pixel of the mixed area.

[0054] The relational-expression generating means may generate theplurality of relational expressions based on a first approximation inwhich the foreground object components contained in the designated pixeldata and the vicinity pixel data are equal, and a second approximationin which the mixture ratio in the mixed area planarly changes withrespect to the position of the pixel of the mixed area.

[0055] The mixture-ratio detection means may detect the mixture ratio bysolving the plurality of relational expressions according to the methodof least squares.

[0056] The relational-expression generating means may generate theplurality of relational expressions by extracting the pixel data of theframe prior to the designated frame as the background pixel data whenthe designated pixel belongs to the covered background area and byextracting the pixel data of the frame subsequent to the designatedframe as the background pixel data when the designated pixel belongs tothe uncovered background area.

[0057] The relational-expression generating means may generate theplurality of relational expressions by extracting, in correspondencewith the designated pixel, mixed pixel data indicating a mixture statein which the plurality of objects are mixed from the designated frameand the peripheral frame based on the motion of the foreground objectand by also extracting, in correspondence with each item of the mixedpixel data, the background pixel data corresponding to the backgroundobject from a frame different from the frame from which the mixed pixeldata is extracted based on the motion of the background object.

[0058] The relational-expression generating means may generate theplurality of relational expressions based on a first approximation inwhich the foreground object components corresponding to the mixed pixeldata are equal and a second approximation in which the mixed pixel dataextracted from the designated frame and the peripheral frame areuniform.

[0059] The relational-expression generating means may generate theplurality of relational expressions by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and by also extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame prior to the frame from which the mixedpixel data is extracted based on the motion of the background object.The covered background area/uncovered background area specifying meansmay specify an area in which the predictive error is greater than orequal to a predetermined threshold as the uncovered background area.

[0060] The relational-expression generating means may generate theplurality of relational expressions by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and also by extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from the frame subsequent to the frame from which themixed pixel data is extracted based on the motion of the backgroundobject. The covered background area/uncovered background area specifyingmeans may specify an area in which the predictive error is greater thanor equal to a predetermined threshold as the covered background area.

[0061] In correspondence with a designated pixel of a designated frameof image data, pixel data of a peripheral frame around the designatedframe is extracted as background pixel data corresponding to abackground object which forms a background among a plurality of objectsof the image data, and also, designated pixel data of the designatedpixel contained in the designated frame is extracted so as to generate aplurality of relational expressions concerning the designated pixelindicating the relationship between the designated pixel data and thebackground pixel data. The mixture ratio indicating the mixture state ofthe plurality of objects in the real world concerning the designatedpixel is detected based on the relational expressions. The predictiveerror is calculated by substituting the detected mixture ratio into therelational expressions. Based on the predictive error, it is specifiedwhether an area to which the designated pixel belongs is a mixed area inwhich the plurality of objects are mixed and is also a coveredbackground area formed at a leading end in the moving direction of aforeground object which forms a foreground among the plurality ofobjects, or is the mixed area and is also an uncovered background areaformed at a trailing end in the moving direction of the foregroundobject. It is specified whether the area to which the designated pixelbelongs is a foreground area consisting of only foreground objectcomponents which form the foreground object or a background areaconsisting of only background object components which form thebackground object.

[0062] With this arrangement, it is possible to specify a backgroundimage area, a moving object image area, and an image area in which themixture of the background image area and the moving object image areaoccurs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0063]FIG. 1 illustrates an embodiment of an image processing apparatusaccording to the present invention.

[0064]FIG. 2 is a block diagram illustrating the image processingapparatus.

[0065]FIG. 3 illustrates the image capturing performed by a sensor.

[0066]FIG. 4 illustrates the arrangement of pixels.

[0067]FIG. 5 illustrates the operation of a detection device.

[0068]FIG. 6A illustrates an image obtained by image-capturing an objectcorresponding to a moving foreground and an object corresponding to astationary background.

[0069]FIG. 6B illustrates a model of an image obtained byimage-capturing an object corresponding to a moving foreground and anobject corresponding to a stationary background.

[0070]FIG. 7 illustrates a background area, a foreground area, a mixedarea, a covered background area, and an uncovered background area.

[0071]FIG. 8 illustrates a model obtained by expanding in the timedirection the pixel values of pixels aligned side-by-side in an imageobtained by image-capturing an object corresponding to a stationaryforeground and an the object corresponding to a stationary background.

[0072]FIG. 9 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0073]FIG. 10 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0074]FIG. 11 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0075]FIG. 12 illustrates an example in which pixels in a foregroundarea, a background area, and a mixed area are extracted.

[0076]FIG. 13 illustrates the relationships between pixels and a modelobtained by expanding the pixel values in the time direction.

[0077]FIG. 14 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0078]FIG. 15 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0079]FIG. 16 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0080]FIG. 17 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0081]FIG. 18 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0082]FIG. 19 is a flowchart illustrating the processing for adjustingthe amount of motion blur.

[0083]FIG. 20 is a block diagram illustrating the configuration of amixture-ratio calculator 103.

[0084]FIG. 21 illustrates an example of the ideal mixture ratio a.

[0085]FIG. 22 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0086]FIG. 23 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0087]FIG. 24 illustrates the selection of pixels.

[0088]FIG. 25 illustrates the selection of pixels.

[0089]FIG. 26 is a block diagram illustrating the configuration of anestimated-mixture-ratio processor 201.

[0090]FIG. 27 is a flowchart illustrating the processing for calculatingthe estimated mixture ratio.

[0091]FIG. 28 is a flowchart illustrating the processing for calculatingthe mixture ratio estimation by using a model according to a coveredbackground area.

[0092]FIG. 29 is a block diagram illustrating another configuration ofthe mixture-ratio calculator 103.

[0093]FIG. 30 illustrates a straight line for approximating the mixtureratio α.

[0094]FIG. 31 illustrates a plane for approximating the mixture ratio α.

[0095]FIG. 32 illustrates the relationships of the pixels in a pluralityof frames when the mixture ratio α is calculated.

[0096]FIG. 33 is a flowchart illustrating the mixture-ratio-estimatingprocessing by using a model corresponding to a covered background area.

[0097]FIG. 34 is a block diagram illustrating still anotherconfiguration of the mixture-ratio calculator 103.

[0098]FIG. 35 is a block diagram illustrating the configuration of anarea specifying unit 104.

[0099]FIG. 36 illustrates the determining processing performed by anuncovered-background-area determining portion 303.

[0100]FIG. 37 illustrates the determining processing performed by theuncovered-background-area determining portion 303.

[0101]FIG. 38 illustrates an example of an input image.

[0102]FIG. 39 illustrates an example of area determining results.

[0103]FIG. 40 illustrates an example of area determining results.

[0104]FIG. 41 illustrates an example of an input image.

[0105]FIG. 42 illustrates an example of area determining results.

[0106]FIG. 43 illustrates an example of area determining results.

[0107]FIG. 44 is a block diagram illustrating another configuration ofthe area specifying unit 104.

[0108]FIG. 45 is a block diagram illustrating still anotherconfiguration of the area specifying unit 104.

[0109]FIG. 46 is a block diagram illustrating a further configuration ofthe area specifying unit 104.

[0110]FIG. 47 is a flowchart illustrating the area specifyingprocessing.

[0111]FIG. 48 is a flowchart illustrating the processing for specifyinga covered background area.

[0112]FIG. 49 is a flowchart illustrating the processing for specifyingan uncovered background area.

[0113]FIG. 50 is a block diagram illustrating an example of theconfiguration of a foreground/background separator 105.

[0114]FIG. 51A illustrates an input image, a foreground component image,and a background component image.

[0115]FIG. 51B illustrates an input image, a foreground component image,and a background component image.

[0116]FIG. 52 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0117]FIG. 53 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0118]FIG. 54 illustrates a model in which pixel values are expanded inthe time direction and the period corresponding to the shutter time isdivided.

[0119]FIG. 55 is a block diagram illustrating an example of theconfiguration of a separating portion 601.

[0120]FIG. 56A illustrates an example of a separated foregroundcomponent image.

[0121]FIG. 56B illustrates an example of a separated backgroundcomponent image.

[0122]FIG. 57 is a flowchart illustrating the processing for separatinga foreground and a background.

[0123]FIG. 58 is a block diagram illustrating an example of theconfiguration of a motion-blur adjusting unit 106.

[0124]FIG. 59 illustrates the unit of processing.

[0125]FIG. 60 illustrates a model in which the pixel values of aforeground component image are expanded in the time direction and theperiod corresponding to the shutter time is divided.

[0126]FIG. 61 illustrates a model in which the pixel values of aforeground component image are expanded in the time direction and theperiod corresponding to the shutter time is divided.

[0127]FIG. 62 illustrates a model in which the pixel values of aforeground component image are expanded in the time direction and theperiod corresponding to the shutter time is divided.

[0128]FIG. 63 illustrates a model in which the pixel values of aforeground component image are expanded in the time direction and theperiod corresponding to the shutter time is divided.

[0129]FIG. 64 illustrates an example of another configuration of themotion-blur adjusting unit 106.

[0130]FIG. 65 is a flowchart illustrating the processing for adjustingthe amount of motion blur contained in a foreground component imageperformed by the motion-blur adjusting unit 106.

[0131]FIG. 66 is a block diagram illustrating an example of anotherconfiguration of the motion-blur adjusting unit 106.

[0132]FIG. 67 illustrates an example of a model in which therelationships between pixel values and foreground components areindicated.

[0133]FIG. 68 illustrates the calculation of foreground components.

[0134]FIG. 69 illustrates the calculation of foreground components.

[0135]FIG. 70 is a flowchart illustrating the processing for eliminatingmotion blur contained in a foreground.

BEST MODE FOR CARRYING OUT THE INVENTION

[0136]FIG. 1 illustrates an embodiment of an image processing apparatusaccording to the present invention. A CPU (Central Processing Unit) 21executes various types of processing according to programs stored in aROM (Read Only Memory) 22 or in a storage unit 28. Programs executed bythe CPU 21 and data are stored in a RAM (Random Access Memory) 23 asrequired. The CPU 21, the ROM 22, and the RAM 23 are connected to eachother by a bus 24.

[0137] An input/output interface 25 is also connected to the CPU 21 viathe bus 24. An input unit 26, which is formed of a keyboard, a mouse, amicrophone, and so on, and an output unit 27, which is formed of adisplay, a speaker, and so on, are connected to the input/outputinterface 25. The CPU 21 executes various types of processing inresponse to a command input from the input unit 26. The CPU 21 thenoutputs an image or sound obtained as a result of the processing to theoutput unit 27.

[0138] The storage unit 28 connected to the input/output interface 25 isformed of, for example, a hard disk, and stores programs executed by theCPU 21 and various types of data. A communication unit 29 communicateswith an external device via the Internet or another network. In thisexample, the communication unit 29 serves as an obtaining unit forobtaining an output of a sensor.

[0139] Alternatively, a program may be obtained via the communicationunit 29 and stored in the storage unit 28.

[0140] A drive 30 connected to the input/output interface 25 drives amagnetic disk 51, an optical disc 52, a magneto-optical disk 53, asemiconductor memory 54, or the like, when such a recording medium isattached to the drive 30, and obtains a program or data stored in thecorresponding medium. The obtained program or data is transferred to thestorage unit 28 and stored therein if necessary.

[0141]FIG. 2 is a block diagram illustrating the image processingapparatus.

[0142] It does not matter whether the individual functions of the imageprocessing apparatus are implemented by hardware or software. That is,the block diagrams of this specification may be hardware block diagramsor software functional block diagrams.

[0143] In this specification, an image to be captured corresponding toan object in the real world is referred to as an image object.

[0144] An input image supplied to the image processing apparatus issupplied to an object extracting unit 101, a mixture-ratio calculator103, an area specifying unit 104, and a foreground/background separator105.

[0145] The object extracting unit 101 extracts a rough image objectcorresponding to a foreground object contained in the input image, andsupplies the extracted image object to a motion detector 102. The objectextracting unit 101 detects, for example, an outline of the foregroundimage object contained in the input image so as to extract a rough imageobject corresponding to the foreground object.

[0146] The object extracting unit 101 extracts a rough image objectcorresponding to a background object contained in the input image, andsupplies the extracted image object to the motion detector 102. Theobject extracting unit 101 extracts a rough image object correspondingto the background object from, for example, the difference between theinput image and the extracted image object corresponding to theforeground object.

[0147] Alternatively, for example, the object extracting unit 101 mayextract the rough image object corresponding to the foreground objectand the rough image object corresponding to the background object fromthe difference between the background image stored in a built-inbackground memory and the input image.

[0148] The motion detector 102 calculates a motion vector of the roughlyextracted image object corresponding to the foreground object accordingto a technique, such as block matching, gradient, phase correlation, orpel-recursive technique, and supplies the calculated motion vector andthe motion-vector positional information (which is information forspecifying the positions of the pixels corresponding to the motionvector) to the mixture-ratio calculator 103 and the motion-bluradjusting unit 106.

[0149] The motion vector output from the motion detector 102 containsinformation corresponding to the amount of movement v.

[0150] The motion detector 102 may output the motion vector of eachimage object, together with the pixel positional information forspecifying the pixels for the image object, to the motion-blur adjustingunit 106.

[0151] The amount of movement v is a value indicating a positionalchange in an image corresponding to a moving object in units of thepixel pitch. For example, if an object image corresponding to aforeground is moving such that it is displayed at a position four pixelsaway from a reference frame when it is positioned in the subsequentframe, the amount of movement v of the object image corresponding to theforeground is 4.

[0152] The object extracting unit 101 and the motion detector 102 areneeded when adjusting the amount of motion blur corresponding to amoving object.

[0153] Based on the input image and the motion vector and the positionalinformation thereof supplied from the motion detector 102, themixture-ratio calculator 103 generates the estimated mixture ratio(hereinafter referred to as the “mixture ratio α”) and the correspondingmixture-ratio related information when it is assumed that the pixelbelongs to a covered background area, which is one portion of the mixedarea, and also generates the estimated mixture ratio, which is themixture ratio to be estimated, and the corresponding mixture-ratiorelated information when it is assumed that the pixel belongs to anuncovered background area, which is the other portion of the mixed area.The mixture-ratio calculator 103 supplies the two generated estimatedmixture ratios and the corresponding mixture-ratio related informationto the area specifying unit 104.

[0154] The mixture ratio α is a value indicating the ratio of the imagecomponents corresponding to the background object (hereinafter also bereferred to as “background components”) to the pixel value as expressedby equation (3), which is shown below.

[0155] Details of the covered background area and the uncoveredbackground area are given below.

[0156] The area specifying unit 104 specifies each pixel of the inputimage as the foreground area, the background area, or the mixed areabased on the input image and the two estimated mixture ratios and thecorresponding mixture-ratio related information supplied from themixture-ratio calculator 103, and supplies information indicating towhich of the foreground area, the background area, or the mixed areaeach pixel belongs (hereinafter referred to as the “area information”)to the foreground/background separator 105 and the motion-blur adjustingunit 106.

[0157] The area specifying unit 104 generates the mixture ratio a basedon the generated area information, and the two estimated mixture ratiosand the corresponding mixture-ratio related information supplied fromthe mixture-ratio calculator 103, and supplies the generated mixtureratio ax to the foreground/background separator 105.

[0158] The foreground/background separator 105 separates the input imageinto a foreground component image formed of only the image componentscorresponding to the foreground object (hereinafter also be referred toas “foreground components”) and a background component image formed ofonly the background components based on the area information and themixture ratio ax supplied from the area specifying unit 104, andsupplies the foreground component image to the motion-blur adjustingunit 106 and a selector 107. The separated foreground component imagemay be set as the final output. A more precise foreground and backgroundcan be obtained compared to a known method in which only a foregroundand a background are specified without considering the mixed area.

[0159] The motion-blur adjusting unit 106 determines the unit ofprocessing indicating at least one pixel contained in the foregroundcomponent image based on the amount of movement v obtained from themotion vector and based on the area information. The unit of processingis data that specifies a group of pixels to be subjected to themotion-blur adjustments.

[0160] Based on the amount by which the motion blur is to be adjusted,which is input into the image processing apparatus, the foregroundcomponent image supplied from the foreground/background separator 105,the motion vector and the positional information thereof supplied fromthe motion detector 102, and the unit of processing, the motion-bluradjusting unit 106 adjusts the amount of motion blur contained in theforeground component image by removing, decreasing, or increasing themotion blur contained in the foreground component image. The motion-bluradjusting unit 106 then outputs the foreground component image in whichamount of motion blur is adjusted to the selector 107. It is notessential that the motion vector and the positional information thereofbe used.

[0161] Motion blur is a distortion contained in an image correspondingto a moving object caused by the movement of an object to be captured inthe real world and the image-capturing characteristics of the sensor.

[0162] The selector 107 selects one of the foreground component imagesupplied from the foreground/background separator 105 and the foregroundcomponent image in which the amount of motion blur is adjusted suppliedfrom the motion-blur adjusting unit 106 based on, for example, aselection signal reflecting a user's selection, and outputs the selectedforeground component image.

[0163] An input image supplied to the image processing apparatus isdiscussed below with reference to FIGS. 3 through 18.

[0164]FIG. 3 illustrates image capturing performed by a sensor. Thesensor is formed of, for example, a CCD (Charge-Coupled Device) videocamera provided with a CCD area sensor, which is a solid-stateimage-capturing device. An object 111 corresponding to a foreground inthe real world moves, for example, horizontally from the left to theright, between an object 112 corresponding to a background and thesensor.

[0165] The sensor captures the image of the object 111 corresponding tothe foreground together with the image of the object 112 correspondingto the background. The sensor outputs the captured image in units offrames. For example, the sensor outputs an image having 30 frames persecond. The exposure time of the sensor can be {fraction (1/30)} second.The exposure time is a period from when the sensor starts convertinginput light into electrical charge until when the conversion from theinput light to the electrical charge is finished. The exposure time isalso referred to as a “shutter time”.

[0166]FIG. 4 illustrates the arrangement of pixels. In FIG. 4, A throughI indicate the individual pixels. The pixels are disposed on a plane ofa corresponding image. One detection device corresponding to each pixelis disposed on the sensor. When the sensor performs image capturing,each detection device outputs a pixel value of the corresponding pixelforming the image. For example, the position of the detection device inthe X direction corresponds to the horizontal direction on the image,while the position of the detection device in the Y directioncorresponds to the vertical direction on the image.

[0167] As shown in FIG. 5, the detection device, which is, for example,a CCD, converts input light into electrical charge during a periodcorresponding to a shutter time, and stores the converted electricalcharge. The amount of charge is almost proportional to the intensity ofthe input light and the period for which the light is input. Thedetection device sequentially adds the electrical charge converted fromthe input light to the stored electrical charge during the periodcorresponding to the shutter time. That is, the detection deviceintegrates the input light during the period corresponding to theshutter time and stores the electrical charge corresponding to theamount of integrated light. It can be considered that the detectiondevice has an integrating function with respect to time.

[0168] The electrical charge stored in the detection device is convertedinto a voltage value by a circuit (not shown), and the voltage value isfurther converted into a pixel value, such as digital data, and isoutput. Accordingly, each pixel value output from the sensor is a valueprojected on a linear space, which is a result of integrating a certainthree-dimensional portion of the object corresponding to the foregroundor the background with respect to the shutter time.

[0169] The image processing apparatus extracts significant informationembedded in the output signal, for example, the mixture ratio a, by thestorage operation of the-sensor. The image processing apparatus adjuststhe amount of distortion, for example, the amount of motion blur, causedby the mixture of the foreground image object itself. The imageprocessing apparatus also adjusts the amount of distortion caused by themixture of the foreground image object and the background image object.

[0170]FIG. 6A illustrates an image obtained by capturing a moving objectcorresponding to a foreground and a stationary object corresponding to abackground. FIG. 6B illustrates an image obtained by capturing a movingobject corresponding to a foreground and a stationary objectcorresponding to a background.

[0171]FIG. 6A illustrates an image obtained by capturing a moving objectcorresponding to a foreground and a stationary object corresponding to abackground. In the example shown in FIG. 6A, the object corresponding tothe foreground is moving horizontally from the left to the right withrespect to the screen.

[0172]FIG. 6B illustrates a model obtained by expanding pixel valuescorresponding to one line of the image shown in FIG. 6A in the timedirection. The horizontal direction shown in FIG. 6B corresponds to thespatial direction X in FIG. 6A.

[0173] The values of the pixels in the background area are formed onlyfrom the background components, that is, the image componentscorresponding to the background object. The values of the pixels in theforeground area are formed only from the foreground components, that is,the image components corresponding to the foreground object.

[0174] The values of the pixels of the mixed area are formed from thebackground components and the foreground components. Since the values ofthe pixels in the mixed area are formed from the background componentsand the foreground components, it may be referred to as a “distortionarea”. The mixed area is further classified into a covered backgroundarea and an uncovered background area.

[0175] The covered background area is a mixed area at a positioncorresponding to the leading end in the direction in which theforeground object is moving, where the background components aregradually covered with the foreground over time.

[0176] In contrast, the uncovered background area is a mixed areacorresponding to the trailing end in the direction in which theforeground object is moving, where the background components graduallyappear over time.

[0177] As discussed above, the image containing the foreground area, thebackground area, or the covered background area or the uncoveredbackground area is input into the area specifying unit 103, themixture-ratio calculator 104, and the foreground/background separator105 as the input image.

[0178]FIG. 7 illustrates the background area, the foreground area, themixed area, the covered background area, and the uncovered backgroundarea discussed above. In the areas corresponding to the image shown inFIG. 6A, the background area is a stationary portion, the foregroundarea is a moving portion, the covered background area of the mixed areais a portion that changes from the background to the foreground, and theuncovered background area of the mixed area is a portion that changesfrom the foreground to the background.

[0179]FIG. 8 illustrates a model obtained by expanding in the timedirection the pixel values of the pixels aligned side-by-side in theimage obtained by capturing the image of the object corresponding to thestationary foreground and the image of the object corresponding to thestationary background. For example, as the pixels aligned side-by-side,pixels arranged in one line on the screen can be selected.

[0180] The pixel values indicated by F01 through F04 shown in FIG. 8 arevalues of the pixels corresponding to the object of the stationaryforeground. The pixel values indicated by B01 through B04 shown in FIG.8 are values of the pixels corresponding to the object of the stationarybackground.

[0181] Time elapses from the top to the bottom in FIG. 8 in the verticaldirection in FIG. 8. The position at the top side of the rectangle inFIG. 8 corresponds to the time at which the sensor starts convertinginput light into electrical charge, and the position at the bottom sideof the rectangle in FIG. 8 corresponds to the time at which theconversion from the input light into the electrical charge is finished.That is, the distance from the top side to the bottom side of therectangle in FIG. 8 corresponds to the shutter time.

[0182] The pixels shown in FIG. 8 are described below assuming that, forexample, the shutter time is equal to the frame size.

[0183] The horizontal direction in FIG. 8 corresponds to the spatialdirection X in FIG. 6A. More specifically, in the example shown in FIG.8, the distance from the left side of the rectangle indicated by “F01”in FIG. 8 to the right side of the rectangle indicated by “B04”, iseight times the pixel pitch, i.e., eight consecutive pixels.

[0184] When the foreground object and the background object arestationary, the light input into the sensor does not change during theperiod corresponding to the shutter time.

[0185] The period corresponding to the shutter time is divided into twoor more portions of equal periods. For example, if the number of virtualdivided portions is 4, the model shown in FIG. 8 can be represented bythe model shown in FIG. 9. The number of virtual divided portions can beset according to the amount of movement v of the object corresponding tothe foreground within the shutter time. For example, the number ofvirtual divided portions is set to 4 when the amount of movement v is 4,and the period corresponding to the shutter time is divided into fourportions.

[0186] The uppermost line in FIG. 9 corresponds to the first dividedperiod from when the shutter has opened. The second line in FIG. 9corresponds to the second divided period from when the shutter hasopened. The third line in FIG. 9 corresponds to the third divided periodfrom when the shutter has opened. The fourth line in FIG. 9 correspondsto the fourth divided period from when the shutter has opened.

[0187] The shutter time divided in accordance with the amount ofmovement v is also hereinafter referred to as the “shutter time/v”.

[0188] When the object corresponding to the foreground is stationary,the light input into the sensor does not change, and thus, theforeground component F01/v is equal to the value obtained by dividingthe pixel value F01 by the number of virtual divided portions.Similarly, when the object corresponding to the foreground isstationary, the foreground component F02/v is equal to the valueobtained by dividing the pixel value F02 by the number of virtualdivided portions, the foreground component F03/v is equal to the valueobtained by dividing the pixel value F03 by the number of virtualdivided portions, and the foreground component F04/v is equal to thevalue obtained by dividing the pixel value F04 by the number of virtualdivided portions.

[0189] When the object corresponding to the background is stationary,the light input into the sensor does not change, and thus, thebackground component B01/v is equal to the value obtained by dividingthe pixel value B 01 by the number of virtual divided portions.Similarly, when the object corresponding to the background isstationary, the background component B02/v is equal to the valueobtained by dividing the pixel value B02 by the number of virtualdivided portions, the background component B03/v is equal to the valueobtained by dividing the pixel value B03 by the number of virtualdivided portions, and the background component B04/v is equal to thevalue obtained by dividing the pixel value B04 by the number of virtualdivided portions.

[0190] More specifically., when the object corresponding to theforeground is stationary, the light corresponding to the foregroundobject input into the sensor does not change during the periodcorresponding to the shutter time. Accordingly, the foreground componentF01/v corresponding to the first portion of the shutter time/v from whenthe shutter has opened, the foreground component F01/v corresponding tothe second portion of the shutter time/v from when the shutter hasopened, the foreground component F01/v corresponding to the thirdportion of the shutter time/v from when the shutter has opened, and theforeground component F01/v corresponding to the fourth portion of theshutter time/v from when the shutter has opened become the same value.The same applies to F02/v through F04/v, as in the case of F01/v.

[0191] When the object corresponding to the background is stationary,the light corresponding to the background object input into the sensordoes not change during the period corresponding to the shutter time.Accordingly, the background component B01/v corresponding to the firstportion of the shutter time/v from when the shutter has opened, thebackground component B01/v corresponding to the second portion of theshutter time/v from when the shutter has opened, the backgroundcomponent B01/v corresponding to the third portion of the shutter time/vfrom when the shutter has opened, and the background component B01/vcorresponding to the fourth portion of the shutter time/v from when theshutter has opened become the same value. The same applies to B02/vthrough B04/v.

[0192] A description is given of the case in which the objectcorresponding to the foreground is moving and the object correspondingto the background is stationary.

[0193]FIG. 10 illustrates a model obtained by expanding in the timedirection the pixel values of the pixels in one line, including acovered background area, when the object corresponding to the foregroundis moving to the right in FIG. 10. In FIG. 10, the amount of movement vis 4. Since one frame is a short period, it can be assumed that theobject corresponding to the foreground is a rigid body moving withconstant velocity. In FIG. 10, the object image corresponding to theforeground is moving such that it is positioned four pixels to the rightwith respect to a reference frame when it is displayed in the subsequentframe.

[0194] In FIG. 10, the pixels from the leftmost pixel to the fourthpixel belong to the foreground area. In FIG. 10, the pixels from thefifth pixel to the seventh pixel from the left belong to the mixed area,which is the covered background area. In FIG. 10, the rightmost pixelbelongs to the background area.

[0195] The object corresponding to the foreground is moving such that itgradually covers the object corresponding to the background over time.Accordingly, the components contained in the pixel values of the pixelsbelonging to the covered background area change from the backgroundcomponents to the foreground components at a certain time during theperiod corresponding to the shutter time.

[0196] For example, the pixel value M surrounded by the thick frame inFIG. 10 is expressed by equation (1) below.

M=B02/v+B02/v+F07/v+F06/v   (1)

[0197] For example, the fifth pixel from the left contains a backgroundcomponent corresponding to one portion of the shutter time/v andforeground components corresponding to three portions of the shuttertime/v, and thus, the mixture ratio a of the fifth pixel from the leftis 1/4. The sixth pixel from the left contains background componentscorresponding to two portions of the shutter time/v and foregroundcomponents corresponding to two portions of the shutter time/v, andthus, the mixture ratio a of the sixth pixel from the left is 1/2. Theseventh pixel from the left contains background components correspondingto three portions of the shutter time/v and a foreground componentcorresponding to one portion of the shutter time/v, and thus, themixture ratio a of the fifth pixel from the left is 3/4.

[0198] It can be assumed that the object corresponding to the foregroundis a rigid body, and the foreground object is moving with constantvelocity such that it is displayed four pixels to the right in thesubsequent frame. Accordingly, for example, the foreground componentF07/v of the fourth pixel from the left in FIG. 10 corresponding to thefirst portion of the shutter time/v from when the shutter has opened isequal to the foreground component of the fifth pixel from the left inFIG. 10 corresponding to the second portion of the shutter time/v fromwhen the shutter has opened. Similarly, the foreground component F07/vis equal to the foreground component of the sixth pixel from the left inFIG. 10 corresponding to the third portion of the shutter time/v fromwhen the shutter has opened, and the foreground component of the seventhpixel from the left in FIG. 10 corresponding to the fourth portion ofthe shutter time/v from when the shutter has opened.

[0199] It can be assumed that the object corresponding to the foregroundis a rigid body, and the foreground object is moving with constantvelocity such that it is displayed four pixels to the right in thesubsequent frame. Accordingly, for example, the foreground componentF06/v of the third pixel from the left in FIG. 10 corresponding to thefirst portion of the shutter time/v from when the shutter has opened isequal to the foreground component of the fourth pixel from the left inFIG. 10 corresponding to the second portion of the shutter time/v fromwhen the shutter has opened. Similarly, the foreground component F06/vis equal to the foreground component of the fifth pixel from the left inFIG. 10 corresponding to the third portion of the shutter time/v fromwhen the shutter has opened, and the foreground component of the sixthpixel from the left in FIG. 10 corresponding to the fourth portion ofthe shutter time/v from when the shutter has opened.

[0200] It can be assumed that the object corresponding to the foregroundis a rigid body, and the foreground object is moving with constantvelocity such that it is displayed four pixels to the right in thesubsequent frame. Accordingly, for example, the foreground componentF05/v of the second pixel from the left in FIG. 10 corresponding to thefirst portion of the shutter time/v from when the shutter has opened isequal to the foreground component of the third pixel from the left inFIG. 10 corresponding to the second portion of the shutter time/v fromwhen the shutter has opened. Similarly, the foreground component F05/vis equal to the foreground component of the fourth pixel from the leftin FIG. 10 corresponding to the third portion of the shutter time/v fromwhen the shutter has opened, and the foreground component of the fifthpixel from the left in FIG. 10 corresponding to the fourth portion ofthe shutter time/v from when the shutter has opened.

[0201] It can be assumed that the object corresponding to the foregroundis a rigid body, and the foreground object is moving with constantvelocity such that it is displayed four pixels to the right in thesubsequent frame. Accordingly, for example, the foreground componentF04/v of the leftmost pixel in FIG. 10 corresponding to the firstportion of the shutter time/v from when the shutter has opened is equalto the foreground component of the second pixel from the left in FIG. 10corresponding to the second portion of the shutter time/v from when theshutter has opened. Similarly, the foreground component F04/v is equalto the foreground component of the third pixel from the left in FIG. 10corresponding to the third portion of the shutter time/v from when theshutter has opened, and the foreground component of the fourth pixelfrom the left in FIG. 10 corresponding to the fourth portion of theshutter time/v from when the shutter has opened.

[0202] Since the foreground area corresponding to the moving objectcontains motion blur as discussed above, it can also be referred to as a“distortion area”.

[0203]FIG. 11 illustrates a model obtained by expanding in the timedirection the pixel values of the pixels in one line including anuncovered background area when the object corresponding to theforeground is moving to the right in FIG. 11. In FIG. 11, the amount ofmovement v is 4. Since one frame is a short period, it can be assumedthat the object corresponding to the foreground is a rigid body movingwith constant velocity. In FIG. 11, the object image corresponding tothe foreground is moving to the right such that it is positioned fourpixels to the right with respect to a reference frame when it isdisplayed in the subsequent frame.

[0204] In FIG. 11, the pixels from the leftmost pixel to the fourthpixel belong to the background area. In FIG. 11, the pixels from thefifth pixel to the seventh pixels from the left belong to the mixedarea, which is an uncovered background area. In FIG. 11, the rightmostpixel belongs to the foreground area.

[0205] The object corresponding to the foreground which covers theobject corresponding to the background is moving such that it isgradually removed from the object corresponding to the background overtime. Accordingly, the components contained in the pixel values of thepixels belonging to the uncovered background area change from theforeground components to the background components at a certain time ofthe period corresponding to the shutter time.

[0206] For example, the pixel value M′ surrounded by the thick frame inFIG. 11 is expressed by equation (2).

M′=F02/v+F01/v+26/v+26/v   (2)

[0207] For example, the fifth pixel from the left contains backgroundcomponents corresponding to three portions of the shutter time/v and aforeground component corresponding to one shutter portion of the shuttertime/v, and thus, the mixture ratio ax of the fifth pixel from the leftis 3/4. The sixth pixel from the left contains background componentscorresponding to two portions of the shutter time/v and foregroundcomponents corresponding to two portions of the shutter time/v, andthus, the mixture ratio α of the sixth pixel from the left is 1/2. Theseventh pixel from the left contains a background componentcorresponding to one portion of the shutter time/v and foregroundcomponents corresponding to three portions of the shutter time/v, andthus, the mixture ratio α of the seventh pixel from the left is 1/4.

[0208] When equations (1) and (2) are generalized, the pixel value M canbe expressed by equation (3). $\begin{matrix}{M = {{\alpha \cdot B} + {\sum\limits_{i}{{Fi}/v}}}} & (3)\end{matrix}$

[0209] In this equation, α is the mixture ratio, B indicates a pixelvalue of the background, and Fi/v designates a foreground component.

[0210] It can be assumed that the object corresponding to the foregroundis a rigid body, which is moving with constant velocity, and the amountof movement is 4. Accordingly, for example, the foreground componentF01/v of the fifth pixel from the left in FIG. 11 corresponding to thefirst portion of the shutter time/v from when the shutter has opened isequal to the foreground component of the sixth pixel from the left inFIG. 11 corresponding to the second portion of the shutter time/v fromwhen the shutter has opened. Similarly, the foreground component F01/vis equal to the foreground component of the seventh pixel from the leftin FIG. 11 corresponding to the third portion of the shutter time/v fromwhen the shutter has opened, and the foreground component of the eighthpixel from the left in FIG. 11 corresponding to the fourth portion ofthe shutter time/v from when the shutter has opened.

[0211] It can be assumed that the object corresponding to the foregroundis a rigid body, which is moving with constant velocity, and the amountof movement v is 4. Accordingly, for example, the foreground componentF02/v of the sixth pixel from the left in FIG. 11 corresponding to thefirst portion of the shutter time/v from when the shutter has opened isequal to the foreground component of the seventh pixel from the left inFIG. 11 corresponding to the second portion of the shutter time/v fromwhen the shutter has opened. Similarly, the foreground component F02/vis equal to the foreground component of the eighth pixel from the leftin FIG. 11 corresponding to the third portion of the shutter time/v fromwhen the shutter has opened.

[0212] It can be assumed that the object corresponding to the foregroundis a rigid body, which is moving with constant velocity, and the amountof movement v is 4. Accordingly, for example, the foreground componentF03/v of the seventh pixel from the left in FIG. 11 corresponding to thefirst portion of the shutter time/v from when the shutter has opened isequal to the foreground component of the eighth pixel from the left inFIG. 11 corresponding to the second portion of the shutter time/v fromwhen the shutter has opened.

[0213] It has been described with reference to FIGS. 9 through 11 thatthe number of virtual divided portions is 4. The number of virtualdivided portions corresponds to the amount of movement v. Generally, theamount of movement v corresponds to the moving speed of the objectcorresponding to the foreground. For example, if the objectcorresponding to the foreground is moving such that it is displayed fourpixels to the right with respect to a certain frame when it ispositioned in the subsequent frame, the amount of movement v is set to4. The number of virtual divided portions is set to 4 in accordance withthe amount of movement v. Similarly, when the object corresponding tothe foreground is moving such that it is displayed six pixels to theleft with respect to a certain frame when it is positioned in thesubsequent frame, the amount of movement v is set to 6, and the numberof virtual divided portions is set to 6.

[0214]FIGS. 12 and 13 illustrate the relationship of the foregroundarea, the background area, and the mixed area which consists of acovered background or an uncovered background, which are discussedabove, to the foreground components and the background componentscorresponding to the divided periods of the shutter time.

[0215]FIG. 12 illustrates an example in which pixels in the foregroundarea, the background area, and the mixed area are extracted from animage containing a foreground corresponding to an object moving in frontof a stationary background. In the example shown in FIG. 12, the objectcorresponding to the foreground indicated by A is horizontally movingwith respect to the screen.

[0216] Frame #n+1 is a frame subsequent to frame #n, and frame #n+2 is aframe subsequent to frame #n+1.

[0217] Pixels in the foreground area, the background area, and the mixedarea are extracted from one of frames #n through #n+2, and the amount ofmovement v is set to 4. A model obtained by expanding the pixel valuesof the extracted pixels in the time direction is shown in FIG. 13.

[0218] Since the object corresponding to the foreground is moving, thepixel values in the foreground area are formed of four differentforeground components corresponding to the shutter time/v. For example,the leftmost pixel of the pixels in the foreground area shown in FIG. 13consists of F01/v, F02/v, F03/v, and F04/v. That is, the pixels in theforeground contain motion blur.

[0219] Since the object corresponding to the background is stationary,light input into the sensor corresponding to the background during theshutter time does not change. In this case, the pixel values in thebackground area do not contain motion blur.

[0220] The pixel values in the mixed area consisting of a coveredbackground area or an uncovered background area are formed of foregroundcomponents and background components.

[0221] A description is given below of a model obtained by expanding inthe time direction the pixel values of the pixels which are alignedside-by-side in a plurality of frames and which are located at the samepositions in the frames when the image corresponding to the object ismoving. For example, when the image corresponding to the object ismoving horizontally with respect to the screen, pixels aligned on thescreen can be selected as the pixels aligned side-by-side.

[0222]FIG. 14 illustrates a model obtained by expanding in the timedirection the pixels which are aligned side-by-side in three frames ofan image obtained by capturing an object corresponding to a stationarybackground and which are located at the same positions in the frames.Frame #n is the frame subsequent to frame #n−1, and frame #n+1 is theframe subsequent to frame #n. The same applies to the other frames.

[0223] The pixel values B01 through B12 shown in FIG. 14 are pixelvalues corresponding to the stationary background object. Since theobject corresponding to the background is stationary, the pixel valuesof the corresponding pixels in frame #n−1 through frame #n+1 do notchange. For example, the pixel in frame #n and the pixel in frame #n+1located at the corresponding position of the pixel having the pixelvalue B05 in frame #n−1 have the pixel value B05.

[0224]FIG. 15 illustrates a model obtained by expanding in the timedirection the pixels which are aligned side-by-side in three frames ofan image obtained by capturing an object corresponding to a foregroundthat is moving to the right in FIG. 15 together with an objectcorresponding to a stationary background and which are located at thesame positions in the frames. The model shown in FIG. 15 contains acovered background area.

[0225] In FIG. 15, it can be assumed that the object corresponding tothe foreground is a rigid body moving with constant velocity, and thatit is moving such that it is displayed four pixels to the right in thesubsequent frame. Accordingly, the amount of movement v is 4, and thenumber of virtual divided portions is 4.

[0226] For example, the foreground component of the leftmost pixel offrame #n−1 in FIG. 15 corresponding to the first portion of the shuttertime/v from when the shutter has opened is F12/v, and the foregroundcomponent of the second pixel from the left in FIG. 15 corresponding tothe second portion of the shutter time/v from when the shutter hasopened is also F12/v. The foreground component of the third pixel fromthe left in FIG. 15 corresponding to the third portion of the shuttertime/v from when the shutter has opened and the foreground component ofthe fourth pixel from the left in FIG. 15 corresponding to the fourthportion of the shutter time/v from when the shutter has opened areF12/v.

[0227] The foreground component of the leftmost pixel of frame #n−1 inFIG. 15 corresponding to the second portion of the shutter time/v fromwhen the shutter has opened is F11/v. The foreground component of thesecond pixel from the left in FIG. 15 corresponding to the third portionof the shutter time/v from when the shutter has opened is also F11/v.The foreground component of the third pixel from the left in FIG. 15corresponding to the fourth portion of the shutter time/v from when theshutter has opened is F11/v.

[0228] The foreground component of the leftmost pixel of frame #n−1 inFIG. 15 corresponding to the third portion of the shutter time/v fromwhen the shutter has opened is F10/v. The foreground component of thesecond pixel from the left in FIG. 15 corresponding to the fourthportion of the shutter time/v from when the shutter has opened is alsoF10/v. The foreground component of the leftmost pixel of frame #n−1 inFIG. 15 corresponding to the fourth portion of the shutter time/v fromwhen the shutter has opened is F09/v.

[0229] Since the object corresponding to the background is stationary,the background component of the second pixel from the left of frame #n−1in FIG. 15 corresponding to the first portion of the shutter time/v fromwhen the shutter has opened is B01/v. The background components of thethird pixel from the left of frame #n−1 in FIG. 15 corresponding to thefirst and second portions of the shutter time/v from when the shutterhas opened are B02/v. The background components of the fourth pixel fromthe left of frame #n−1 in FIG. 15 corresponding to the first throughthird portions of the shutter time/v from when the shutter has openedare B03/v.

[0230] In frame #n−1 in FIG. 15, the leftmost pixel from the left,belongs to the foreground area, and the second through fourth pixelsfrom the left belong to the mixed area, which is a covered backgroundarea.

[0231] The fifth through twelfth pixels from the left of frame #n−1 inFIG. 15 belong to the background area, and the pixel values thereof areB04 through B11, respectively.

[0232] The first through fifth pixels from the left in frame #n in FIG.15 belong to the foreground area. The foreground component in theshutter time/v in the foreground area of frame #n is any one of F05/vthrough F12/v.

[0233] It can be assumed that the object corresponding to the foregroundis a rigid body moving with constant velocity, and that it is movingsuch that the foreground image is displayed four pixels to the right inthe subsequent frame. Accordingly, the foreground component of the fifthpixel from the left of frame #n in FIG. 15 corresponding to the firstportion of the shutter time/v from when the shutter has opened is F12/v,and the foreground component of the sixth pixel from the left in FIG. 15corresponding to the second portion of the shutter time/v from when theshutter has opened is also F12/v. The foreground component of theseventh pixel from the left in FIG. 15 corresponding to the thirdportion of the shutter time/v from when the shutter has opened and theforeground component of the eighth pixel from the left in FIG. 15corresponding to the fourth portion of the shutter time/v from when theshutter has opened are F12/v.

[0234] The foreground component of the fifth pixel from the left offrame #n in FIG. 15 corresponding to the second portion of the shuttertime/v from when the shutter has opened is F11/v. The foregroundcomponent of the sixth pixel from the left in FIG. 15 corresponding tothe third portion of the shutter time/v from when the shutter has openedis also F11/v. The foreground component of the seventh pixel from theleft in FIG. 15 corresponding to the fourth portion of the shuttertime/v from when the shutter has opened is F11/v.

[0235] The foreground component of the fifth pixel from the left offrame #n in FIG. 15 corresponding to the third portion of the shuttertime/v from when the shutter has opened is F10/v. The foregroundcomponent of the sixth pixel from the left in FIG. 15 corresponding tothe fourth portion of the shutter time/v from when the shutter hasopened is also F10/v. The foreground component of the fifth pixel fromthe left of frame #n in FIG. 15 corresponding to the fourth portion ofthe shutter time/v from when the shutter has opened is F09/v.

[0236] Since the object corresponding to the background is stationary,the background component of the sixth pixel from the left of frame #n inFIG. 15 corresponding to the first portion of the shutter time/v fromwhen the shutter has opened is B05/v. The background components of theseventh pixel from the left of frame #n in FIG. 15 corresponding to thefirst and second portions of the shutter time/v from when the shutterhas opened are B06/v. The background components of the eighth pixel fromthe left of frame #n in FIG. 15 corresponding to the first through thirdportion of the shutter time/v from when the shutter has opened areB07/v.

[0237] In frame #n in FIG. 15, the sixth through eighth pixels from theleft belong to the mixed area, which is a covered background area.

[0238] The ninth through twelfth pixels from the left of frame #n inFIG. 15 belong to the background area, and the pixel values thereof areB08 through B11, respectively.

[0239] The first through ninth pixels from the left in frame #n+1 inFIG. 15 belong to the foreground area. The foreground component in theshutter time/v in the foreground area of frame #n+1 is any one of F01/vthrough F12/v.

[0240] It can be assumed that the object corresponding to the foregroundis a rigid body moving with constant velocity, and that it is movingsuch that the foreground image is displayed four pixels to the right inthe subsequent frame. Accordingly, the foreground component of the ninthpixel from the left of frame #n+1 in FIG. 15 corresponding to the firstportion of the shutter time/v from when the shutter has opened is F12/v,and the foreground component of the tenth pixel from the left in FIG. 15corresponding to the second portion of the shutter time/v from when theshutter has opened is also F12/v. The foreground component of theeleventh pixel from the left in FIG. 15 corresponding to the thirdportion of the shutter time/v from when the shutter has opened and theforeground component of the twelfth pixel from the left in FIG. 15corresponding to the fourth portion of the shutter time/v from when theshutter has opened are F12/v.

[0241] The foreground component of the ninth pixel from the left offrame #n+1 in FIG. 15 corresponding to the second portion of the shuttertime/v from when the shutter has opened is F11/v. The foregroundcomponent of the tenth pixel from the left in FIG. 15 corresponding tothe third portion of the shutter time/v from when the shutter has openedis also F11/v. The foreground component of the eleventh pixel from theleft in FIG. 15 corresponding to the fourth portion of the shuttertime/v from when the shutter has opened is F11/v.

[0242] The foreground component of the ninth pixel from the left offrame #n+1 in FIG. 15 corresponding to the third portion of the shuttertime/v from when the shutter has opened is F10/v. The foregroundcomponent of the tenth pixel from the left in FIG. 15 corresponding tothe fourth portion of the shutter time/v from when the shutter hasopened is also F10/v. The foreground component of the ninth pixel fromthe left of frame #n+1 in FIG. 15 corresponding to the fourth portion ofthe shutter time/v from when the shutter has opened is F09/v.

[0243] Since the object corresponding to the background is stationary,the background component of the tenth pixel from the left of frame #n+1in FIG. 15 corresponding to the first portion of the shutter time/v fromwhen the shutter has opened is B09/v. The background components of theeleventh pixel from the left of frame #n+1 in FIG. 15 corresponding tothe first and second portions of the shutter time/v from when theshutter has opened are B10/v. The background components of the twelfthpixel from the left of frame #n+1 in FIG. 15 corresponding to the firstthrough third portion of the shutter time/v from when the shutter hasopened are B11/v.

[0244] In frame #n+1 in FIG. 15, the tenth through twelfth pixels fromthe left belong to the mixed area, which is a covered background area.

[0245]FIG. 16 is a model of an image obtained by extracting theforeground components from the pixel values shown in FIG. 15.

[0246]FIG. 17 illustrates a model obtained by expanding in the timedirection the pixels which are aligned side-by-side in three frames ofan image obtained by capturing an object corresponding to a foregroundthat is moving to the right in FIG. 17 together with an objectcorresponding to a stationary background and which are located at thesame positions in the frames. The model shown in FIG. 17 contains anuncovered background area.

[0247] In FIG. 17, it can be assumed that the object corresponding tothe foreground is a rigid body moving with constant velocity, and thatit is moving such that it is displayed four pixels to the right in thesubsequent frame. Accordingly, the amount of movement v is 4.

[0248] For example, the foreground component of the leftmost pixel offrame #n−1 in FIG. 17 corresponding to the first portion of the shuttertime/v from when the shutter has opened is F13/v, and the foregroundcomponent of the second pixel from the left in FIG. 17 corresponding tothe second portion of the shutter time/v from when the shutter hasopened is also F13/v. The foreground component of the third pixel fromthe left in FIG. 17 corresponding to the third portion of the shuttertime/v from when the shutter has opened and the foreground component ofthe fourth pixel from the left in FIG. 17 corresponding to the fourthportion of the shutter time/v from when the shutter has opened areF13/v.

[0249] The foreground component of the second pixel from the left offrame #n−1 in FIG. 17 corresponding to the first portion of the shuttertime/v from when the shutter has opened is F14/v. The foregroundcomponent of the third pixel from the left in FIG. 17 corresponding tothe second portion of the shutter time/v from when the shutter hasopened is also F14/v. The foreground component of the third pixel fromthe left in FIG. 17 corresponding to the first portion of the shuttertime/v from when the shutter has opened is F15/v.

[0250] Since the object corresponding to the background is stationary,the background components of the leftmost pixel of frame #n−1 in FIG. 17corresponding to the second through fourth portions of the shuttertime/v from when the shutter has opened are B25/v. The backgroundcomponents of the second pixel from the left of frame #n−1 in FIG. 17corresponding to the third and fourth portions of the shutter time/vfrom when the shutter has opened are B26/v. The background component ofthe third pixel from the left of frame #n−1 in FIG. 17 corresponding tothe fourth portion of the shutter time/v from when the shutter hasopened is B27/v.

[0251] In frame #n−1 in FIG. 17, the leftmost pixel through the thirdpixel belong to the mixed area, which is an uncovered background area.

[0252] The fourth through twelfth pixels from the left of frame #n−1 inFIG. 17 belong to the foreground area. The foreground component of theframe is any one of F13/v through F24/v.

[0253] The leftmost pixel through the fourth pixel from the left offrame #n in FIG. 17 belong to the background area, and the pixel valuesthereof are B25 through B28, respectively.

[0254] It can be assumed that the object corresponding to the foregroundis a rigid body moving with constant velocity, and that it is movingsuch that it is displayed four pixels to the right in the subsequentframe. Accordingly, the foreground component of the fifth pixel from theleft of frame #n in FIG. 17 corresponding to the first portion of theshutter time/v from when the shutter has opened is F13/v, and theforeground component of the sixth pixel from the left in FIG. 17corresponding to the second portion of the shutter time/v from when theshutter has opened is also F13/v. The foreground component of theseventh pixel from the left in FIG. 17 corresponding to the thirdportion of the shutter time/v from when the shutter has opened and theforeground component of the eighth pixel from the left in FIG. 17corresponding to the fourth portion of the shutter time/v from when theshutter has opened are F13/v.

[0255] The foreground component of the sixth pixel from the left offrame #n in FIG. 17 corresponding to the first portion of the shuttertime/v from when the shutter has opened is F14/v. The foregroundcomponent of the seventh pixel from the left in FIG. 17 corresponding tothe second portion of the shutter time/v from when the shutter hasopened is also F14/v. The foreground component of the eighth pixel fromthe left in FIG. 17 corresponding to the first portion of the shuttertime/v from when the shutter has opened is F15/v.

[0256] Since the object corresponding to the background is stationary,the background components of the fifth pixel from the left of frame #nin FIG. 17 corresponding to the second through fourth portions of theshutter time/v from when the shutter has opened are B 29/v. Thebackground components of the sixth pixel from the left of frame #n inFIG. 17 corresponding to the third and fourth portions of the shuttertime/v from when the shutter has opened are B30/v. The backgroundcomponent of the seventh pixel from the left of frame #n in FIG. 17corresponding to the fourth portion of the shutter time/v from when theshutter has opened is B31/v.

[0257] In frame #n in FIG. 17, the fifth pixel through the seventh pixelfrom the left belong to the mixed area, which is an uncovered backgroundarea.

[0258] The eighth through twelfth pixels from the left of frame #n inFIG. 17 belong to the foreground area. The value in the foreground areaof frame #n corresponding to the period of the shutter time/v is any oneof F13/v through F20/v.

[0259] The leftmost pixel through the eighth pixel from the left offrame #n+1 in FIG. 17 belong to the background area, and the pixelvalues thereof are B25 through B32, respectively.

[0260] It can be assumed that the object corresponding to the foregroundis a rigid body moving with constant velocity, and that it is movingsuch that it is displayed four pixels to the right in the subsequentframe. Accordingly, the foreground component of the ninth pixel from theleft of frame #n+1 in FIG. 17 corresponding to the first portion of theshutter time/v from when the shutter has opened is F13/v, and theforeground component of the tenth pixel from the left in FIG. 17corresponding to the second portion of the shutter time/v from when theshutter has opened is also F13/v. The foreground component of theeleventh pixel from the left in FIG. 17 corresponding to the thirdportion of the shutter time/v from when the shutter has opened and theforeground component of the twelfth pixel from the left in FIG. 17corresponding to the fourth portion of the shutter time/v from when theshutter has opened are F13/v.

[0261] The foreground component of the tenth pixel from the left offrame #n+1 in FIG. 17 corresponding to the first portion of the shuttertime/v from when the shutter has opened is F14/v. The foregroundcomponent of the eleventh pixel from the left in FIG. 17 correspondingto the second portion of the shutter time/v from when the shutter hasopened is also F14/v. The foreground component of the twelfth pixel fromthe left in FIG. 17 corresponding to the first portion of the shuttertime/v from when the shutter has opened is F15/v.

[0262] Since the object corresponding to the background is stationary,the background components of the ninth pixel from the left of frame #n+1in FIG. 17 corresponding to the second through fourth portions of theshutter time/v from when the shutter has opened are B33/v. Thebackground components of the tenth pixel from the left of frame #n+1 inFIG. 17 corresponding to the third and fourth portions of the shuttertime/v from when the shutter has opened are B34/v. The backgroundcomponent of the eleventh pixel from the left of frame #n+1 in FIG. 17corresponding to the fourth portion of the shutter time/v from when theshutter has opened is B35/v.

[0263] In frame #n+1 in FIG. 17, the ninth through eleventh pixels fromthe left in FIG. 17 belong to the mixed area, which is an uncoveredbackground area.

[0264] The twelfth pixel from the left of frame #n+1 in FIG. 17 belongsto the foreground area. The foreground component in the shutter time/vin the foreground area of frame #n+1 is any one of F13 through F16,respectively.

[0265]FIG. 18 illustrates a model of an image obtained by extracting theforeground components from the pixel values shown in FIG. 17.

[0266] Referring back to FIG. 2, based on the input image and the motionvector and the positional information thereof supplied from the motiondetector 102, the mixture-ratio calculator 103 generates the estimatedmixture ratio and the corresponding mixture-ratio related informationwhen it is assumed that the pixel belongs to the covered backgroundarea, and also generates the estimated mixture ratio, which is themixture ratio to be estimated, and the corresponding mixture-ratiorelated information when it is assumed that the pixel belongs to theuncovered background area. The mixture-ratio calculator 103 supplies thetwo generated estimated mixture ratios and the correspondingmixture-ratio related information to the area specifying unit 104.

[0267] The area specifying unit 104 specifies each pixel of the inputimage as the foreground area, the background area, or the mixed areabased on the input image and the two estimated mixture ratios and thecorresponding mixture-ratio related information supplied from themixture-ratio calculator 103, and supplies the area informationindicating to which of the foreground area, the background area, or themixed area each pixel belongs to the foreground/background separator 105and the motion-blur adjusting unit 106.

[0268] The foreground/background separator 105 extracts the foregroundcomponent image consisting of only the foreground components based onthe pixel values of a plurality of frames, the area information, and themixture ratio α, and supplies the foreground component image to themotion-blur adjusting unit 106.

[0269] The motion-blur adjusting unit 106 adjusts the amount of motionblur contained in the foreground component image based on the foregroundcomponent image supplied from the foreground/background separator 105,the motion vector supplied from the motion detector 102, and the areainformation supplied from the area specifying unit 104, and then outputsthe foreground component image in which motion blur is adjusted.

[0270] The processing for adjusting the amount of motion blur performedby the image processing apparatus is described below with reference tothe flowchart of FIG. 19. In step S11, based on the input image and themotion vector and the positional information thereof supplied from themotion detector 102, the mixture-ratio calculator 103 calculates theestimated mixture ratio and the corresponding mixture-ratio relatedinformation when it is assumed that the pixel belongs to the coveredbackground area, and also calculates the estimated mixture ratio and thecorresponding mixture-ratio related information when it is assumed thatthe pixel belongs to the uncovered background area. The mixture-ratiocalculator 103 supplies the two calculated estimated mixture ratios andthe corresponding mixture-ratio related information to the areaspecifying unit 104. Details of the mixture-ratio calculation processingare given below.

[0271] In step S12, the area specifying unit 104 performs, based on theinput image and the two estimated mixture ratios and the correspondingmixture-ratio related information supplied from the mixture-ratiocalculator 103, area specifying processing for generating areainformation indicating to which of the foreground area, the backgroundarea, the covered background area, or the uncovered background area eachpixel of the input image belongs. Details of the area specifyingprocessing are given below. The area specifying unit 104 generates themixture ratio a based on the generated area information, and the twoestimated mixture ratios and the corresponding mixture-ratio relatedinformation supplied from the mixture-ratio calculator 103, and suppliesthe generated mixture ratio a to the foreground/background separator105.

[0272] In step S13, the foreground/background separator 105 extracts theforeground components from the input image based on the area informationand the mixture ratio a, and supplies the foreground components to themotion-blur adjusting unit 106 as the foreground component image.

[0273] In step S14, the motion-blur adjusting unit 106 generates, basedon the motion vector and the area information, the unit of processingthat indicates the positions of consecutive pixels disposed in themoving direction and belonging to any of the uncovered background area,the foreground area, and the covered background area, and adjusts theamount of motion blur contained in the foreground componentscorresponding to the unit of processing. Details of the processing foradjusting the amount of motion blur are given below.

[0274] In step S15, the image processing apparatus determines whetherthe processing is finished for the whole screen. If it is determinedthat the processing is not finished for the whole screen, the processproceeds to step S14, and the processing for adjusting the amount ofmotion blur for the foreground components corresponding to the unit ofprocessing is repeated.

[0275] If it is determined in step S15 that the processing is finishedfor the whole screen, the processing is completed.

[0276] In this manner, the image processing apparatus is capable ofadjusting the amount of motion blur contained in the foreground byseparating the foreground and the background. That is, the imageprocessing apparatus is capable of adjusting the amount of motion blurcontained in sampled data indicating the pixel values of the foregroundpixels.

[0277] The configuration of each of the mixture-ratio calculator 103,the area specifying unit 104, the foreground/background separator 105,and the motion-blur adjusting unit 106 is described below.

[0278]FIG. 20 is a block diagram illustrating the configuration of themixture-ratio calculator 103. An estimated-mixture-ratio processor 201calculates an estimated mixture ratio for each pixel by calculationcorresponding to a model of a covered background area based on themotion vector and the positional information thereof supplied from themotion detector 102 and the input image, and outputs the estimatedmixture ratio together with the mixture-ratio related information, whichis determined with the calculation of the estimated mixture ratio. Themixture-ratio related information output from theestimated-mixture-ratio processor 201 is, for example, the sum offoreground components.

[0279] An estimated-mixture-ratio processor 202 calculates an estimatedmixture ratio for each pixel by calculation corresponding to a model ofan uncovered background area based on the motion vector and thepositional information thereof supplied from the motion detector 102 andthe input image, and outputs the estimated mixture ratio together withthe mixture-ratio related information, which is determined with thecalculation of the estimated mixture ratio. The mixture-ratio relatedinformation output from the estimated-mixture-ratio processor 202 is,for example, the sum of foreground components.

[0280] Since it can be assumed that the object corresponding to theforeground is moving with constant velocity within the shutter time, themixture ratio α of the pixels belonging to a mixed area exhibits thefollowing characteristics. That is, the mixture ratio α linearly changesaccording to the positional change in the pixels. If the positionalchange in the pixels is one-dimensional, a change in the mixture ratio αcan be represented linearly. If the positional change in the pixels istwo-dimensional, a change in the mixture ratio α can be represented on aplane.

[0281] Since the period of one frame is short, it can be assumed thatthe object corresponding to the foreground is a rigid body moving withconstant velocity.

[0282] The gradient of the mixture ratio α is inversely proportional tothe amount of movement v within the shutter time of the foreground.

[0283] An example of the ideal mixture ratio α is shown in FIG. 21. Thegradient l of the ideal mixture ratio α in the mixed area can berepresented by the reciprocal of the amount of movement v.

[0284] As shown in FIG. 21, the ideal mixture ratio α has the value of 1in the background area, the value of 0 in the foreground area, and thevalue of greater than 0 and smaller than 1 in the mixed area.

[0285] In the example shown in FIG. 22, the pixel value C06 of theseventh pixel from the left in frame #n can be indicated by equation (4)by using the pixel value P06 of the seventh pixel from the left in frame#n−1. $\begin{matrix}\begin{matrix}{{C06} = {{{B06}/v} + {{B06}/v} + {{F01}/v} + {{F02}/v}}} \\{= {{{P06}/v} + {{P06}/v} + {{F01}/v} + {{F02}/v}}} \\{= {{{2/v} \cdot {P06}} + {\sum\limits_{i = 1}^{2}{{Fi}/v}}}}\end{matrix} & (4)\end{matrix}$

[0286] In equation (4), the pixel value C06 is indicated by a pixelvalue M of the pixel in the mixed area, while the pixel value P06 isindicated by a pixel value B of the pixel in the background area. Thatis, the pixel value M of the pixel in the mixed area and the pixel valueB of the pixel in the background area can be represented by equations(5) and (6), respectively.

M=C06   (5)

B=P06   (6)

[0287] In equation (4), 2/v corresponds to the mixture ratio α. Sincethe amount of movement v is 4, the mixture ratio a of the seventh pixelfrom the left in frame #n is 0.5.

[0288] As discussed above, the pixel value C in the designated frame #nis considered as the pixel value in the mixed area, while the pixelvalue P of frame #n−1 prior to frame #n is considered as the pixel valuein the background area. Accordingly, equation (3) indicating the mixtureratio a can be represented by equation (7):

C=α·P+f   (7)

[0289] where f in equation (7) indicates the sum of the foregroundcomponents Σ_(i)Fi/v contained in the designated pixel. The variablescontained in equation (7) are two factors, i.e., the mixture ratio α andthe sum f of the foreground components.

[0290] Similarly, a model obtained by expanding in the time directionthe pixel values in which the amount of movement is 4 and the number ofvirtual divided portions is 4 in an uncovered background area is shownin FIG. 23.

[0291] As in the representation of the covered background area, in theuncovered background area, the pixel value C of the designated frame #nis considered as the pixel value in the mixed area, while the pixelvalue N of frame #n+1 subsequent to frame #n is considered as thebackground area. Accordingly, equation (3) indicating the mixture ratioax can be represented by equation (8).

C=α·N+f   (8)

[0292] The embodiment has been described, assuming that the backgroundobject is stationary. However, equations (4) through (8) can be appliedto the case in which the background object is moving by using the pixelvalue of a pixel located corresponding to the amount of movement v ofthe background. It is now assumed, for example, in FIG. 22 that theamount of movement v of the object corresponding to the background is 2,and the number of virtual divided portions is 2. In this case, when theobject corresponding to the background is moving to the right in FIG.22, the pixel value B of the pixel in the background area in equation(6) is represented by a pixel value P04.

[0293] Since equations (7) and (8) each contain two variables, themixture ratio a cannot be determined without modifying the equations.

[0294] Accordingly, the mixture ratio ax is determined by establishingan equation concerning a set of a pixel belonging to the mixed area andthe corresponding pixel belonging to the background area in accordancewith the amount of movement v of the foreground object.

[0295] As the amount of movement v, the motion vector and the positionalinformation thereof supplied from the motion vector 102 are utilized.

[0296] The calculation for the estimated mixture ratio performed by theestimated-mixture-ratio processor 201 by using the amount of movement vbased on a model corresponding to the covered background area isdescribed below.

[0297] In the example shown in FIG. 22 corresponding to the coveredbackground area, equation (9) holds true for P02 of frame #n−1, andequation (10) holds true for C06 of frame #n. $\begin{matrix}{{P02} = {{{2/v} \cdot {B02}} + {\sum\limits_{i = 1}^{2}{{Fi}/v}}}} & (9) \\{{C06} = {{{2/v} \cdot {B06}} + {\sum\limits_{i = 1}^{2}{{Fi}/v}}}} & (10)\end{matrix}$

[0298] In equations (9) and (10), the values corresponding to themixture ratio a are the same, i.e., 2/v. In equations (9) and (10), thevalues corresponding to the sum of the foreground components are thesame, i.e., $\sum\limits_{i = 1}^{2}{{Fi}/{v.}}$

[0299] That is, the mixture ratios α of P02 of frame #n−1 and C06 offrame #n are the same, and the sums of the foreground components of P02of frame #n−1 and C06 of frame #n are the same. Accordingly, it can beproved that C06 of frame #n corresponds to P02 of frame #n−1 accordingto the movement of the foreground object.

[0300] By assuming that the foreground object is moving with constantvelocity and the foreground components are uniform over a plurality offrames, it is possible to select a plurality of sets, each setconsisting of a pixel belonging to the mixed area and the correspondingpixel belonging to the background area having the same mixture ratio αand the same sum of the foreground components, according to the amountof movement v of the foreground object. For example, five sets, each setconsisting of a pixel belonging to the mixed area and the correspondingpixel belonging to the background area, may be selected.

[0301] For example, as shown in FIG. 24, pixels Mt1 through Mt5belonging to the mixed area and corresponding pixels Bt1 through Bt5belonging to the background area can be selected from frame #n−3 throughframe #n+2 in accordance with the amount of movement v of the foregroundobject. In FIG. 24, the white dots indicate pixels considered to belongto the background area, and the black dots indicate pixels considered tobelong to the mixed area.

[0302] Equations (11) through (15) hold true for the pixels Mt1 throughMt5 and the pixels Bt1 through Bt5.

Mt1=α·Bt1+f   (11)

Mt2=α·Bt2+f   (12)

Mt3=α·Bt3+f   (13)

Mt4=α·Bt4+f   (14)

Mt5=α·Bt5+f   (15)

[0303] f in equations (11) through (15) designates the sum of theforeground components Σ_(i)Fi/v.

[0304] Since the five equations (11) through (15) contain the commonvariables, i.e., the mixture ratio α and the sum f of the foregroundcomponents, the method of least squares can be applied to equations (11)through (15) to determine the mixture ratio α and the sum f of theforeground components.

[0305] For example, the estimated-mixture-ratio processor 201 prestoresnormal equations for calculating the mixture ratio α and the sum f ofthe foreground components, and sets pixel values belonging to the mixedarea and the corresponding pixel values belonging to the background areain the stored normal equations, thereby calculating the mixture ratio αand the sum f of the foreground components according to a matrixsolution.

[0306] If the background is moving, as indicated by an example of FIG.25, the estimated-mixture-ratio processor 201 sets pixel valuesbelonging to the mixed area and the corresponding pixel values belongingto the background area in the normal equations in accordance with theamount of movement v′, and calculates the mixture ratio α and the sum fof the foreground components according to a matrix solution. In FIG. 25,the white dots indicate pixels considered to belong to the backgroundarea, and the black dots designate the pixels considered to belong tothe mixed area.

[0307] As discussed above, the estimated-mixture-ratio processor 201calculates the estimated mixture ratio by using the amount of movement vbased on a model corresponding to the covered background area.

[0308] Similarly, the estimated-mixture-ratio processor 202 calculatesthe estimated mixture ratio by using the amount of movement v based on amodel corresponding to the uncovered background area. In the uncoveredbackground area, the corresponding pixel belonging to the backgroundarea is selected from the frame subsequent to the frame of a designatedpixel.

[0309]FIG. 26 is a block diagram illustrating the configuration of theestimated-mixture-ratio processor 201 for calculating the estimatedmixture ratio by using the amount of movement v based on a modelcorresponding to the covered background area.

[0310] A normal-equation adder 221 sets, based on the motion vector andthe positional information thereof supplied from the motion detector102, pixel values belonging to the mixed area and the correspondingpixel values belonging to the background area contained in an image of Mframes of the input image in prestored normal equations. Thenormal-equation adder 221 supplies the normal equations in which thepixel values belonging to the mixed area and the corresponding pixelvalues belonging to the background area are set to a calculator 222.

[0311] The calculator 222 solves the normal equations in which the pixelvalues are set supplied from the normal-equation adder 221 by applying amatrix solution, for example, a sweep-out method (Gauss-Jordanelimination) so as to obtain the estimated mixture ratio, and outputsthe calculated estimated mixture ratio. The calculator 222 outputs thesum of the foreground components, which is determined together with thecalculation of the estimated mixture ratio, as the mixture-ratio relatedinformation.

[0312] As discussed above, the estimated-mixture-ratio processor 201calculates the estimated mixture ratio by using the amount of movement vbased on a model corresponding to the covered background area. Theestimated-mixture-ratio processor 201 outputs the sum of the foregroundcomponents as the mixture-ratio related information.

[0313] The estimated-mixture-ratio processor 202 has a configurationsimilar to the estimated-mixture-ratio processor 201, and an explanationthereof is thus omitted.

[0314] As described above, based on the input image and the motionvector and the positional information thereof supplied from the motiondetector 102, the mixture-ratio calculator 103 is able to generate theestimated mixture ratio and the corresponding mixture-ratio relatedinformation when it is assumed that the pixel belongs to the coveredbackground area, and is also able to generate the estimated mixtureratio, which is the mixture ratio to be estimated, and the correspondingmixture-ratio related information when it is assumed that the pixelbelongs to the uncovered background area.

[0315] The estimated-mixture-ratio calculation processing performed bythe mixture-ratio calculator 103 is described below with reference tothe flowchart of FIG. 27. In step S201, the estimated-mixture-ratioprocessor 201 performs the mixture-ratio estimating processing by usinga model corresponding to the covered background area based on the inputimage and the motion vector and the positional information thereofsupplied from the motion detector 102. Details of the mixture-ratioestimating processing are described below with reference to theflowchart of FIG. 28.

[0316] In step S202, the estimated-mixture-ratio processor 202 performsthe mixture-ratio estimating processing by using a model correspondingto the uncovered background area based on the input image and the motionvector and the positional information thereof supplied form the motiondetector 102.

[0317] In step S203, the mixture-ratio calculator 103 determines whetherthe mixture ratios have been estimated for the whole frame. If it isdetermined that the mixture ratios have not been estimated for the wholeframe, the process returns to step S201, and the processing forestimating the mixture ratio of the subsequent pixel is executed.

[0318] If it is determined in step S203 that the mixture ratios havebeen estimated for the whole frame, the processing is completed.

[0319] As discussed above, the mixture-ratio calculator 103 is able tocalculate the estimated mixture ratio for each pixel based on the motionvector and the positional information thereof supplied from the motiondetector 102 and the input image.

[0320] A description is given below, with reference to the flowchart ofFIG. 28, of the estimated-mixture-ratio calculating processing performedby the estimated-mixture-ratio processor 201 by using a modelcorresponding to the covered background area in step S201 of FIG. 27.

[0321] In step S221, the normal-equation adder 221 reads the motionvector and the positional information supplied from the motion detector102 so as to obtain the amount of movement v.

[0322] In step S222, the normal-equation adder 221 selects the pixelsfrom input M frames of images based on the amount of movement v, andsets the pixel values of the selected pixels in the prestored normalequations.

[0323] In step S223, the normal-equation adder 221 determines whetherthe pixel values have been set for the target pixel. If it is determinedthat the pixel values have not been set for the target pixel, theprocess returns to step S222, and the processing for setting the pixelvalues is repeated.

[0324] If it is determined in step S223 that the pixel values have beenset for the target pixel, the process proceeds to step S224. In stepS224, the normal-equation adder 221 supplies the normal equations inwhich the pixel values are set to the calculator 222, and the calculator222 solves the normal equations by a sweep-out method (Gauss-Jordanelimination) so as to calculate the estimated mixture ratio. Theprocessing is then completed. The calculator 222 outputs the sum of theforeground components corresponding to each pixel, which is determinedtogether with the calculation of the estimated mixture ratio, as themixture-ratio related information.

[0325] As discussed above, the estimated-mixture-ratio processor 201 isable to calculate the estimated mixture ratio.

[0326] The mixture-ratio estimating processing performed by theestimated-mixture-ratio processor 202 by using a model corresponding tothe uncovered background area in step S202 of FIG. 27 is similar to theprocessing indicated by the flowchart of FIG. 28 by using the normalequations corresponding to the model of the uncovered background area,and an explanation there of is thus omitted.

[0327]FIG. 29 is a block diagram illustrating another configuration ofthe mixture-ratio calculator 103. The mixture-ratio calculator 103configured as shown in FIG. 29 does not use a motion vector.

[0328] An estimated-mixture-ratio processor 241 calculates, based on theinput image, the estimated mixture ratio of each pixel by thecalculation corresponding to a model of the covered background area, andoutputs the estimated mixture ratio together with the mixture-ratiorelated information, which is calculated together with the calculationof the estimated mixture ratio. The mixture-ratio related informationoutput from the estimated-mixture-ratio processor 241 is, for example,the sum of the foreground components or the gradient of the mixtureratio.

[0329] An estimated-mixture-ratio processor 242 calculates, based on theinput image, the estimated mixture ratio of each pixel by thecalculation corresponding to a model of the uncovered background area,and outputs the estimated mixture ratio together with the mixture-ratiorelated information, which is calculated together with the calculationof the estimated mixture ratio. The mixture-ratio related informationoutput from the estimated-mixture-ratio processor 242 is, for example,the sum of the foreground components or the gradient of the mixtureratio.

[0330] The mixture-ratio estimating processing performed by theestimated-mixture-ratio processor 241 and the estimated-mixture-ratioprocessor 242 is described below with reference to FIGS. 30 and 32.

[0331] As discussed with reference to FIGS. 22 and 23, since equations(7) and (8) each contain the two variables, the mixture ratio α cannotbe determined without modifying equations (7) and (8).

[0332] The mixture ratio α linearly changes in accordance with a changein the position of the pixels because the object corresponding to theforeground is moving with constant velocity. By utilizing thischaracteristic, the estimated-mixture-ratio processor 241 or theestimated-mixture-ratio processor 242 sets an equation in which themixture ratio a and the sum f of the foreground components areapproximated in the spatial direction. Also, by utilizing a plurality ofsets of the pixel values of the pixels belonging to the mixed area andthe pixel values of the pixels belonging to the background area, theequations in which the mixture ratio α and the sum f of the foregroundcomponents are approximated are solved.

[0333] When a change in the mixture ratio α is approximated as astraight line, the mixture ratio α can be expressed by equation (16).

α=il+p   (16)

[0334] In equation (16), i is the index in the spatial direction whenthe position of the designated pixel is set to 0. l is the gradient ofthe mixture ratio α. p is the intercept of the straight line of themixture ratio α, and is also the mixture ratio α of the designatedpixel. In equation (16), the index i is known, and the gradient l andthe intercept p are unknown.

[0335] The relationship among the index i, the gradient l, and theintercept p is shown in FIG. 30. In FIG. 30, the white dot indicates thedesignated pixel and the black dots indicate the proximity pixels.

[0336] By approximating the mixture ratio α as equation (16), aplurality of different mixture ratios α for a plurality of pixels can beexpressed by two variables. In the example shown in FIG. 30, the fivemixture ratios for five pixels are expressed by the two variables, i.e.,the gradient l and the intercept p.

[0337] When the mixture ratio α is approximated in the plane shown inFIG. 31, equation (16) is expanded into the plane by considering themovement v corresponding to the two directions, i.e., the horizontaldirection and the vertical direction of the image, and the mixture ratioα can be expressed by equation (17). In FIG. 31, the white dot indicatesthe designated pixel.

α=jm+kq+p   (17 )

[0338] In equation (17), j is the index in the horizontal direction andk is the index in the vertical direction when the position of thedesignated pixel is set to 0. In equation (17), m designates thehorizontal gradient of the mixture ratio α in the plane, and q indicatesthe vertical gradient of the mixture ratio α in the plane. In equation(17), p indicates the intercept of the mixture ratio α in the plane.

[0339] For example, in frame #n shown in FIG. 22, equations (18) through(20) can hold true for C05 through C07, respectively.

C05=α05·B05/v+f05   (18)

C06=α06·B06/v+f06   (19)

C07=α07·B07/v+f07   (20)

[0340] Assuming that the foreground components positioned in closeproximity with each other are equal to each other, i.e., that F01through F03 are equal, equation (21) holds true by replacing F01 throughF03 by Fc.

f(x)=(1−α(x))·Fc   (21)

[0341] In equation (21), x indicates the position in the spatialdirection

[0342] When α(x) is replaced by equation (17), equation (21) can beexpressed by equation (22). $\begin{matrix}\begin{matrix}{{f(x)} = {\left( {1 - \left( {{jm} + {kq} + p} \right)} \right) \cdot {Fc}}} \\{= {{j \cdot \left( {{- m} \cdot {Fc}} \right)} + {k \cdot \left( {{- q} \cdot {Fc}} \right)} + \left( {\left( {1 - p} \right) \cdot {Fc}} \right)}} \\{= {{js} + {kt} + u}}\end{matrix} & (22)\end{matrix}$

[0343] In equation (22), (−m·Fc), (−q·Fc), and (1−p)·Fc are replaced, asexpressed by equations (23) through (25), respectively.

s=−m·Fc   (23)

t=−q·Fc   (24)

u=(1−p)·Fc   (25)

[0344] In equation (22), j is the index in the horizontal direction andk is the index in the vertical direction when the position of thedesignated pixel is 0.

[0345] As discussed above, since it can be assumed that the objectcorresponding to the foreground is moving with constant velocity withinthe shutter period, and that the foreground components positioned inclose proximity with each other are uniform, the sum of the foregroundcomponents can be approximated by equation (22).

[0346] When the mixture ratio a is approximated by a straight line, thesum of the foreground components can be expressed by equation (26).

f(x)=is+u   (26)

[0347] By replacing the mixture ratio α and the sum of the foregroundcomponents in equation (16) by using equations (17) and (22), the pixelvalue M can be expressed by equation (27). $\begin{matrix}\begin{matrix}{M = {{\left( {{jm} + {kq} + p} \right) \cdot B} + {js} + {kt} + u}} \\{= {{{jB} \cdot m} + {{kB} \cdot q} + {B \cdot p} + {j \cdot s} + {k \cdot t} + u}}\end{matrix} & (27)\end{matrix}$

[0348] In equation (27), unknown variables are six factors, such as thehorizontal gradient m of the mixture ratio α in the plane, the verticalgradient q of the mixture ratio α in the plane, and the intercepts p, s,t, and u of the mixture ratio α in the plane.

[0349] The pixel value M and the pixel value B are set in equation (27)in accordance with the pixels close to the designated pixel, and then, aplurality of equations in which the pixel value M and the pixel value Bare set are solved by the method of least squares, thereby calculatingthe mixture ratio α.

[0350] It is now assumed, for example, that the horizontal index j ofthe designated pixel is set to 0, and the vertical index k of thedesignated pixel is set to 0. In this case, when the pixel value M orthe pixel value B is set in the equation corresponding to equation (27)for 3×3 pixels located in the proximity with the designated pixel,equations (28) through (36) are obtained.

M _(−1,−1)=(−1)·B _(−1,−1) ·m+(−1)·B _(−1,−1) ·q+B _(−1,−1)·p+(−1)·s·s+(−1)·t+u   (28)

M _(0,−1)=(0)·B _(0,−1) ·m+(−1)·B _(0,−1) ·q+B _(0,−1) ·p+(0)·s+(−1)·t+u  (29)

M _(−1,−1)=(+1)·B _(−1,−1) ·m·(−1) B _(−1,−1) ·q+B _(+1,−1)·p+(+1)·s+(−1)·t+u   (30)

M _(−1,0)=(−1)·B _(−1,0) ·m+(0)·B _(−1,0) ·q+B _(−1,0) ·p+(−1)·s+(0)·t+u  (31)

M _(0,0)=(0)·B _(0,0) ·m+(0)·B _(0,0) ·q+B _(0,0) p+(0)·s+(0)·t+u   (32)

M _(−1,0)=(+1)·B _(+1,0) ·m+(0)·B _(+1,0) ·q+B _(+1,0) ·p+(+1)·s+(0)·t⇄u  (33)

 M _(−1,+1)=(−1)·B _(−1,+1) ·m+(+1)·B _(−1,+1) ·q+B _(−1,+1)·p+(−1)·s+(+1)·t+u   (34)

M _(0,+1)=(0)·B _(0,+1) ·m+(+1)·B _(0,+1) ·q+B _(0,+1) ·p+(0)·s+(+1)·t+u  (35)

M _(+1,+1)=(+1)·B _(+1,+1) ·m+(+1)·B _(+1,+1) ·q+B _(+1,+1)·p+(+1)·s+(+1)·t+u   (36)

[0351] Since the horizontal index j of the designated pixel is 0, andthe vertical index k of the designated pixel is 0, the mixture ratio αof the designated pixel is equal to the value when j is 0 and k is 0 inequation (17), i.e., the mixture ratio α is equal to the intercept p inequation (17).

[0352] Accordingly, based on the nine equations (28) through (36), thehorizontal gradient m, the vertical gradient q, and the intercepts p, s,t, and u are calculated by the method of least squares, and theintercept p is output as the mixture ratio α.

[0353] A specific process for calculating the mixture ratio α byapplying the method of least squares is as follows.

[0354] When the index i and the index k are expressed by a single indexx, the relationship among the index i, the index k, and the index x canbe expressed by equation (37).

x=(j+1)·3+(k+1)   (37)

[0355] It is now assumed that the horizontal gradient m, the verticalgradient q, and the intercepts p, s, t, and u are expressed by variablesw0, w1, w2, w3, w4, and w5, respectively, and jB, kB, B, j, k and 1 areexpressed by a0, a1, a2, a3, a4, and a5, respectively. In considerationof the error ex, equations (28) through (36) can be modified intoequation (38). $\begin{matrix}{{M\quad x} = {{\sum\limits_{y = 0}^{5}{{ay} \cdot {wy}}} + {ex}}} & (38)\end{matrix}$

[0356] In equation (38), x is any one of the integers from 0 to 8.

[0357] Equation (39) can be found from equation (38). $\begin{matrix}{{ex} = {{M\quad x} - {\sum\limits_{y = 0}^{5}{{ay} \cdot {wy}}}}} & (39)\end{matrix}$

[0358] Since the method of least squares is applied, the square sum E ofthe error is defined as follows, as expressed by equation (40).$\begin{matrix}{E = {\sum\limits_{x = 0}^{8}{ex}^{2}}} & (40)\end{matrix}$

[0359] In order to minimize the error, the partial differential value ofthe variable Wv with respect to the square sum E of the error should be0. v is any one of the integers from 0 to 5. Thus, wy is determined sothat equation (41) is satisfied. $\begin{matrix}\begin{matrix}{\frac{\partial E}{\partial{Wv}} = {2 \cdot {\sum\limits_{x = 0}^{8}{{ex} \cdot \frac{\partial{ex}}{\partial{Wv}}}}}} \\{= {{2 \cdot {\sum\limits_{x = 0}^{8}{{ex} \cdot {av}}}} = 0}}\end{matrix} & (41)\end{matrix}$

[0360] By substituting equation (39) into equation (41), equation (42)is obtained. $\begin{matrix}{{\sum\limits_{x = 0}^{8}\left( {{av} \cdot {\sum\limits_{y = 0}^{5}{{ay} \cdot {Wy}}}} \right)} = {\sum\limits_{x = 0}^{8}{{{av} \cdot M}\quad x}}} & (42)\end{matrix}$

[0361] For example, the sweep-out method (Gauss-Jordan elimination) isapplied to the normal equations consisting of six equations obtained bysubstituting one of the integers from 0 to 5 into v in equation (42),thereby obtaining wy. As stated above, w0 is the horizontal gradient m,w1 is the vertical gradient q, w2 is the intercept p, w3 is s, w4 is t,and w5 is u.

[0362] As discussed above, by applying the method of least squares tothe equations in which the pixel value M and the pixel value B are set,the horizontal gradient m, the vertical gradient q, and the interceptsp, s, t, and u can be determined.

[0363] The intercept p is the mixture ratio α when indexes i and k are0, i.e., when the intercept p is located at the center position. Thus,the intercept P is output.

[0364] A description has been given, with reference to equations (28)through (36), by assuming that the pixel value of the pixel contained inthe mixed area is M, and the pixel value of the pixel contained in thebackground area is B. In this case, it is necessary to set normalequations for each of the cases where the designated pixel is containedin the covered background area, or the designated pixel is contained inthe uncovered background area.

[0365] For example, if the mixture ratio α of the pixel contained in thecovered background area in frame #n shown in FIG. 22 is determined, C04through C08 of the pixels in frame #n and the pixel values P04 throughP08 of the pixels in frame #n−1 are set in the normal equations.

[0366] If the mixture ratio α of the pixels contained in the uncoveredbackground area in frame #n shown in FIG. 23 is determined, C28 throughC32 of the pixels in frame #n and the pixel values N28 through N32 ofthe pixels in frame #n+1 are set in the normal equations.

[0367] Moreover, if, for example, the mixture ratio α of the pixelcontained in the covered background area shown in FIG. 32 is calculated,the following equations (43) through (51) are set. In FIG. 32, the whitedots indicate pixels to belong to the background, and the black dotsindicate pixels to belong to the mixed area. The pixel value of thepixel for which the mixture ratio α is calculated is Mc5.

Mc1=(−1)·Bc1·m+(−1)·Bc1·q+Bc1·p+(−1)·s+(−1)·t+u   (43)

Mc2=(0)·Bc 2·m+(−1)·Bc2·q+Bc2·p+(0)·s+(−1)·t+u   (44)

Mc3=(+1)·Bc3·m+(−1)·Bc3·q+Bc3·p+(+1)·s+(−1)·t+u   (45)

Mc4=(−1)·Bc4·m+(0)·Bc4· 1+Bc4·p+(−1)·s+(0)·t+u   (46)

Mc5=(0)·Bc5·m+(0)·Bc5·q+Bc5·p+(0)·s+(0)·t+u   (47)

Mc6=(+1)·Bc6·m+(0)·Bc6·q+Bc6·p+(−1)·s+(0)·t+u   (48)

Mc7=(−1)·Bc7·m+(+1)·Bc7·q+Bc7·p+(−1)·s+(+1)·t+u   (49)

Mc8=(0)·Bc8·m+(+1)·Bc8·q+Bc8·p+(0)·s+(+1)·t+u   (50)

Mc9=(+1)·Bc9·m+(+1)·Bc9·q+Bc9·p+(+1)·s+(+1)·t+u   (51)

[0368] For calculating the mixture ratio α of the pixel contained in thecovered background area in frame #n, the pixel values Bc1 through Bc9 ofthe pixels of the background area in frame #n−1 in equations (43)through (51), respectively, corresponding to the pixels in frame #n areused.

[0369] When, for example, the mixture ratio α of the pixel contained inthe uncovered background area shown in FIG. 32 is calculated, thefollowing equations (52) through (60) are set. The pixel value of thepixel for which the mixture ratio α is calculated is Mu5.

Mu1=(−1)·Bu1·m+(−1)·Bu1·q+Bu 1·p+(−1)·s+(−1)·t+u   (52)

Mu2=(0)·Bu2·m+(−1)·Bu2·q+Bu2·p+(0)·s+(−1)·t+u   (53)

Mu3=(+1)·Bu3·m+(−1)·Bu3·q+Bu3·p+(+1)·s+(−1)·t+u   (54)

Mu4=(−1)·Bu4·m+(0)·Bu4·q+Bu4·p+(−1)·s+(0)·t+u   (55)

Mu5=(0)·Bu5·m+(0)·Bu5+q+Bu5·p+(0)·s+(0)·t+u   (56)

Mu6=(+1)·Bu6·m+(0)·Bu6·q+Bu6·p+(+1)·s+(+1)·s+(0)·t+u   (57)

Mu7=(−1)·Bu7·m+(+1)·Bu7·q+Bu7·p+(−1)·s+(+1)·t+u   (58)

Mu8=(0)·Bu8·m+(+1)·Bu8·q+Bu8·p+(0)·s+(+1)·t+u   (59)

Mu9=(+1)·Bu9·m+(+1)·Bu0·q+Bu9·p+(+1)·s+(+1)·t+u   (60)

[0370] For calculating the mixture ratio α of the pixel contained in theuncovered background area in frame #n, the pixel values Bu1 through Bu9of the pixels of the background area in frame #n+1 in equations (52)through (60), respectively, corresponding to the pixels in frame #n areused.

[0371] The mixture-ratio estimation processor 241 and the mixture-ratioestimation processor 242 are configured similarly to the mixture-ratioprocessor 201, and an explanation thereof is thus omitted.

[0372] The processing for calculating the estimated mixture ratioperformed by the mixture-ratio calculator 103 configured as shown inFIG. 29 is similar to the processing discussed with reference to theflowchart of FIG. 27, and an explanation thereof is thus omitted.

[0373] A description is now given, with reference to the flowchart ofFIG. 33, of the mixture-ratio estimating processing by using a model ofthe covered background area in step S202 of FIG. 27.

[0374] In step S241, the estimated-mixture-ratio processor 241 sets thepixel value contained in the input image in a normal equationcorresponding to a model of the covered background area.

[0375] In step S242, the estimated-mixture-ratio processor 241determines whether the setting of the target pixels is finished. If itis determined that the setting of the target pixels is not finished, theprocess returns to step S241, and the processing for setting the pixelvalues in the normal equation is repeated.

[0376] If it is determined in step S242 that the setting for the targetpixels is finished, the process proceeds to step S243. In step S243, theestimated-mixture-ratio processor 241 calculates the estimated mixtureratio by solving the normal equations in which the pixels values areset, and outputs the calculated mixture ratio. Theestimated-mixture-ratio processor 241 outputs the sum of the foregroundcomponents and the gradient of the estimated mixture ratio, which aredetermined together with the calculation of the estimated mixture ratio,as the mixture-ratio related information.

[0377] As discussed above, the estimated-mixture-ratio processor 241 isable to calculate the estimated mixture ratio based on the input image.The estimated-mixture-ratio processor 241 outputs the sum of theforeground components and the gradient of the estimated mixture ratio asthe mixture-ratio related information.

[0378] The mixture-ratio estimating processing performed by theestimated-mixture-ratio processor 242 by using a model corresponding tothe uncovered background area is similar to the processing using thenormal equations corresponding to a model of the uncovered backgroundarea indicated by the flowchart of FIG. 33, and an explanation thereofis thus omitted.

[0379]FIG. 34 is a block diagram illustrating still anotherconfiguration of the mixture-ratio calculator 103 for estimating themixture ratio from an input image, which is input as a component signal.

[0380] In this specification, the component means individual signalcomponents of a component signal, such as a luminance signal, achrominance signal, and an RGB (Red-green-blue) signal.

[0381] The following description is given based on an example in whichcomponent 1 is a luminance value Y, component 2 is a color difference U,and component 3 is a color difference V.

[0382] An estimated-mixture-ratio processor 241-1 calculates theestimated mixture ratio for each pixel based on component 1 of the inputimage according to the calculation corresponding to a model of a coveredbackground area, and outputs the estimated mixture ratio together withthe mixture-ratio related information, which is determined with thecalculation of the estimated mixture ratio. The mixture-ratio relatedinformation output from the estimated-mixture-ratio processor 241-1 is,for example, the sum of the foreground components and the gradient ofthe mixture ratio.

[0383] An estimated-mixture-ratio processor 242-1 calculates theestimated mixture ratio for each pixel based on component 1 of the inputimage according to the calculation corresponding to a model of anuncovered background area, and outputs the estimated mixture ratiotogether with the mixture-ratio related information, which is determinedwith the calculation of the estimated mixture ratio. The mixture-ratiorelated information output from the estimated-mixture-ratio processor242-1 is, for example, the sum of the foreground components and thegradient of the mixture ratio.

[0384] An estimated-mixture-ratio processor 241-2 calculates theestimated mixture ratio for each pixel based on component 2 of the inputimage according to the calculation corresponding to a model of thecovered background area, and outputs the estimated mixture ratiotogether with the mixture-ratio related information, which is determinedwith the calculation of the estimated mixture ratio.

[0385] An estimated-mixture-ratio processor 242-2 calculates theestimated mixture ratio for each pixel based on component 2 of the inputimage according to the calculation corresponding to a model of theuncovered background area, and outputs the estimated mixture ratiotogether with the mixture-ratio related information, which is determinedwith the calculation of the estimated mixture ratio.

[0386] An estimated-mixture-ratio processor 241-3 calculates theestimated mixture ratio for each pixel based on component 3 of the inputimage according to the calculation corresponding to a model of thecovered background area, and outputs the estimated mixture ratiotogether with the mixture-ratio related information, which is determinedwith the calculation of the estimated mixture ratio.

[0387] An estimated-mixture-ratio processor 242-3 calculates theestimated mixture ratio for each pixel based on component 3 of the inputimage according to the calculation corresponding to a model of theuncovered background area, and outputs the estimated mixture ratiotogether with the mixture-ratio related information, which is determinedwith the calculation of the estimated mixture ratio.

[0388] As discussed above, the mixture-ratio calculator 103 configuredas shown in FIG. 34 is able to calculate for each component, based onthe input image, which is input as the component signal, the estimatedmixture ratio by using a model of the covered background area and theestimated mixture ratio by using a model of the uncovered backgroundarea. The mixture-ratio calculator 103 outputs the mixture-ratio relatedinformation, such as the sum of the foreground components and thegradient of the estimated mixture ratio, for each componentcorresponding to the estimated mixture ratio calculated by the modelcorresponding to the covered background area and the estimated mixtureratio calculated by using the model corresponding to the uncoveredbackground area.

[0389] When estimating the mixture ratios from the input image, which isinput as the component signal, the mixture-ratio calculator 103 maycalculate the estimated mixture ratio by using a model corresponding tothe covered background area and the estimated mixture ratio by using amodel corresponding to the uncovered background area for each componentaccording to the processing by the estimated-mixture-ratio processor 201or 202, and outputs the corresponding mixture-ratio related informationtogether with the estimated mixture ratios.

[0390] The embodiment has been described, assuming that the objectcorresponding to the background is stationary. However, theabove-described mixture-ratio calculation processing can be applied evenif the image corresponding to the background area contains motion. Forexample, if the image corresponding to the background area is uniformlymoving, the mixture-ratio calculator 103 shifts the overall image inaccordance with this motion, and performs processing in a manner similarto the case in which the object corresponding to the background isstationary. If the image corresponding to the background area containslocally different motions, the mixture-ratio calculator 103 selects thepixels corresponding to the motions as the pixels belonging to the mixedarea, and executes the above-described processing.

[0391] The area specifying unit 104 is described below.

[0392]FIG. 35 is a block diagram illustrating the configuration of thearea specifying unit 104. A predictive-error calculating portion 301calculates the error value (predictive error value corresponding to theestimated mixture ratio) for each pixel based on the mixture-ratiorelated information corresponding to the estimated mixture ratiocalculated by using the model of the covered background area and theestimated mixture ratio calculated by using the model of the coveredbackground area, and supplies the calculated error value to anuncovered-background-area determining portion 303.

[0393] For example, when the mixture-ratio calculator 103 estimates themixture ratio by applying the method of least squares to equations (11)through (15), the predictive-error calculating portion 301 calculatesthe least square sum of the errors, which indicates the error value S,by the calculation corresponding to equation (61), based on themixture-ratio related information, which is the sum of the foregroundcomponents, corresponding to the estimated mixture ratio calculated bythe model of the covered background area and the estimated mixture ratiocalculated by the model of the covered background area. $\begin{matrix}{S = {\sum\limits_{t}\left\{ {M - \left( {{\alpha \cdot B} + {\sum\limits_{i}{{Fi}/v}}} \right)} \right\}^{2}}} & (61)\end{matrix}$

[0394] In equation (61), α indicates the estimated mixture ratio, and tindicates the number of frames used for calculating the mixture ratio.$\sum\limits_{i}{{Fi}/v}$

[0395] designates the sum of the foreground components, which is themixture-ratio related information.

[0396] A predictive-error calculating portion 302 calculates the errorvalue for each pixel based on the mixture-ratio related informationcorresponding to the estimated mixture ratio calculated by using a modelof the uncovered background area and the estimated mixture ratiocalculated by using a model of the uncovered background area, andsupplies the calculated error value to a covered-background-areadetermining portion 304.

[0397] The predictive-error calculating portions 301 and 302 maycalculate the error value for each pixel by using blocks, eachconsisting of a plurality of pixels, such as 5×5-pixel blocks.

[0398] The predictive-error calculating portions 301 and 302 may presett, or may obtain t from the mixture-ratio calculator 103 as themixture-ratio related information.

[0399] The uncovered-background-area determining portion 303 determinesfor each pixel whether the error value supplied from thepredictive-error calculating portion 301 is greater than or equal to aprestored threshold Th. If it is determined that the error value isgreater than or equal to the threshold Th, the uncovered-background-areadetermining portion 303 determines that the designated pixel belongs tothe uncovered background area, and sets a flag indicating the uncoveredbackground area in correspondence with the designated pixel. Theuncovered-background-area determining portion 303 supplies the flagindicating the uncovered background area, which is set for each pixel,to a synthesizer 306.

[0400] The covered-background-area determining portion 304 determinesfor each pixel whether the error value supplied from thepredictive-error calculating portion 302 is greater than or equal to theprestored threshold Th. If it is determined that the error value isgreater than or equal to the threshold Th, the covered-background-areadetermining portion 304 determines that the designated pixel belongs tothe covered background area, and sets a flag indicating the coveredbackground area in the designated pixel. The covered-background-areadetermining portion 304 supplies the flag indicating the coveredbackground area, which is set for each pixel, to the synthesizer 306.

[0401] A foreground/background area determining portion 305 determineswhether the pixel belongs to the foreground area or the background area.

[0402] For example, the foreground/background area determining portion305 determines whether the designated pixel is moving based on thedifference between the pixel value of the designated pixel of thedesignated frame #n and the pixel value of the pixel corresponding tothe designated pixel of frame #n−1. The foreground/background areadetermining portion 305 determines whether the designated pixel ismoving based on the difference between the pixel value of the designatedpixel of the designated frame #n and the pixel value of the pixelcorresponding to the designated pixel of frame #n+1.

[0403] If it is determined that the designated pixel from frame #n−1 toframe #n is moving, and that the designated pixel from frame #n to frame#n+1 is moving, the foreground/background area determining portion 305determines that the designated pixel belongs to the foreground area.

[0404] For example, if it is determined that the designated pixel fromframe #n−1 to #n is stationary, and that the designated pixel from frame#n to frame #n+1 is stationary, the foreground/background areadetermining portion 305 determines that the designated pixel belongs tothe background area.

[0405] The foreground/background area determining portion 305 supplies aflag indicating the foreground area and a flag indicating the backgroundarea, which are set for each pixel, to the synthesizer 306.

[0406] The synthesizer 306 synthesizes area information for each pixelindicating one of the uncovered background area, the covered backgroundarea, the foreground area, and the background area based on the flagindicating the uncovered background area supplied from theuncovered-background-area determining portion 303, the flag indicatingthe covered background area supplied from the covered-background-areadetermining portion 304, and the flag indicating the foreground area andthe flag indicating the background area supplied from theforeground/background area determining portion 305. The synthesizer 306supplies the synthesized area information to a mixture-ratio determiningportion 307, and also outputs the area information.

[0407] A mixture-ratio determining portion 307 determines the mixtureratio α based on the area information supplied from the synthesizer 306.More specifically, the mixture-ratio determining portion 307 sets 0 inthe mixture ratio α when the designated pixel belongs to the foregroundarea. The mixture-ratio determining portion 307 sets 1 in the mixtureratio α when the designated pixel belongs to the background area. Whenthe designated pixel belongs to the covered background area, themixture-ratio determining portion 307 sets the estimated mixture ratiocalculated by the model of the covered background area in the mixtureratio α. When the designated pixel belongs to the uncovered backgroundarea, the mixture-ratio determining portion 307 sets the estimatedmixture ratio calculated by the model of the uncovered background areain the mixture ratio α. The mixture-ratio determining portion 307outputs the mixture ratio α determined based on the area information.

[0408] The determining processing performed by theuncovered-background-area determining portion 303 is described belowwith reference to FIGS. 36 and 37.

[0409] As shown in FIG. 36, since the object corresponding to thebackground is stationary, the pixel value of the designated pixelbelonging to the background area of the designated frame #n is equal tothe pixel value of the pixel corresponding to the designated pixel inframe #n+1, which is subsequent to frame #n. In FIG. 36, W indicates thebackground area. Similarly, since the object corresponding to thebackground is stationary, the pixel value of the pixel of frame #n+1indicated by the motion vector based on the designated pixel is equal tothe pixel value of the corresponding pixel of frame #n+2.

[0410] Accordingly, the estimated mixture ratio calculated by the modelof the covered background area corresponding to the pixel belonging tothe background area becomes almost 1, and the sum of the foregroundcomponents becomes almost 0.

[0411] Thus, the error value S calculated by equation (61) becomesalmost 0.

[0412] In FIG. 36, since the designated pixel belonging to theforeground area indicated by X is motion-compensated, the pixel value ofthe designated pixel of the designated frame #n is equal to the pixelvalue of the pixel of frame #n+1 indicated by the motion vector based onthe designated pixel. Since the foreground object has a strongcorrelation in the spatial direction, the values of the foregroundcomponents are almost the same.

[0413] Accordingly, the estimated mixture ratio and the least square sumof the errors of the sum of the foreground components calculated by themethod of least squares become relatively small values, though, strictlyspeaking, this is not proved based on a physical model.

[0414] Naturally, in the covered background area indicated by Y in FIG.36, the estimated mixture ratio calculated by the method of leastsquares and the least square sum of the errors of the sum of theforeground components become almost 0.

[0415] In contrast, as shown in FIG. 37, the foreground componentscontained in the pixel value of the designated pixel of the designatedframe #n belonging to the uncovered background area indicated by Z inFIG. 37 are different from the foreground components contained in thepixel value of the corresponding pixel of frame #n+1, which issubsequent to frame #n. Similarly, the foreground components containedin the pixel value of the pixel of frame #n+1 indicated by the motionvector based on the designated pixel are different from the foregroundcomponents contained in the pixel value of the corresponding pixel offrame #n+2.

[0416] When determining the solution by setting the estimated mixtureratio and the sum of the foreground components to be unknown variablesaccording to the method of least squares, the sum of the foregroundcomponents contained in the pixel value set in the equation cannot becalculated because it is changed.

[0417] Accordingly, the estimated mixture ratio and the least square sumof the errors of the sum of the foreground components, which arecalculated based on the model of the covered background area accordingto the method of least squares, become greater values when thedesignated pixel belongs to the uncovered background area.

[0418] Accordingly, the uncovered-background-area determining portion303 is able to determine whether the designated pixel belongs to theuncovered background area by making a determination as to whether theerror value S of the estimated mixture ratio and the sum of theforeground components, which are calculated based on the model of thecovered background area according to the method of least squares, isgreater than or equal to the threshold Th.

[0419] Similarly, the covered-background-area determining portion 304 isable to determine whether the designated pixel belongs to the coveredbackground area by making a determination as to whether the error valueS of the estimated mixture ratio and the sum of the foregroundcomponents, which are calculated based on the model of the uncoveredbackground area according to the method of least squares, is greaterthan or equal to the threshold Th.

[0420]FIGS. 38 through 43 illustrate input images and examples of theresults of the area determinations performed by the area specifying unit104.

[0421]FIG. 38 illustrates an input image. In the input image shown inFIG. 38, the foreground object is moving from the left to the right inthe drawing.

[0422] The image shown in FIG. 39 is the result obtained by making adetermination for each pixel of the input image shown in FIG. 38 by thearea specifying unit 104 by setting the threshold Th to be 70 based onthe estimated mixture ratio and the sum of the foreground components,which are calculated by the mixture-ratio calculator 103 by using sevenframes.

[0423] The image shown in FIG. 40 is the result obtained by making adetermination for each 5×5-pixel block of the input image shown in FIG.38 by the area specifying unit 104 by assuming that the mixture ratio inthe same block is uniform and by setting the threshold Th of the sum ofthe error values S of each block to be 750 and by setting the thresholdTh of the error value S of each pixel within the block to be 10 based onthe estimated mixture ratio and the sum of the foreground components,which are calculated by the mixture-ratio calculator 103 by using threeframes.

[0424]FIG. 41 illustrates an input image. In the input image shown inFIG. 41, the foreground object is moving from the left to the right inthe drawing.

[0425] The image shown in FIG. 42 is the result obtained by making adetermination for each pixel of the input image shown in FIG. 41 by thearea specifying unit 104 by setting the threshold Th to be 70 based onthe estimated mixture ratio and the sum of the foreground components,which are calculated by the mixture-ratio calculator 103 by using sevenframes.

[0426] The image shown in FIG. 43 is the result obtained by making adetermination for each 5×5-pixel block of the input image shown in FIG.41 by the area specifying unit 104 by assuming that the mixture ratio inthe same block is uniform and by setting the threshold Th of the sum ofthe error values S of each block to be 750 and by setting the thresholdTh of the error value S of each pixel within the block to be 10 based onthe estimated mixture ratio and the sum of the foreground components,which are calculated by the mixture-ratio calculator 103 by using threeframes.

[0427] In FIGS. 39 through 43, the covered background area is positionedat the leading end in the direction in which the foreground object ismoving with respect to the foreground area, and the uncovered backgroundarea is positioned at the trailing end in the direction in which theforeground object is moving with respect to the foreground area.

[0428] As shown in FIGS. 38 through 43, the area specifying unit 104 isable to determine the areas almost precisely.

[0429] A description is given below of the processing of the areaspecifying unit 104 when the mixture-ratio calculator 103 estimates themixture ratio by applying the method of least squares to equations (28)through (36) and outputs the data indicating the gradient of theestimated mixture ratio as the mixture-ratio related informationtogether with the estimated mixture ratio.

[0430] The pixel value M of the designated pixel is expressed byequation (62) according to equation (27).

[0431]M=(jm+kq+p)·B+j·s+k·t+u   (62)

[0432] In equation (62), j indicates the index in the horizontaldirection and k indicates the index in the vertical direction when theposition of the designated pixel is set to 0. In equation (62), mdesignates the horizontal gradient in the plane of the mixture ratio α,q is the vertical gradient in the plane of the mixture ratio α, and pindicates the intercept of the plane of the mixture ratio α. In equation(62), s, t, and u are variables indicating the relationship between m,q, and p and the foreground components, as expressed by equations (23)through (25).

[0433] The predictive-error calculating portion 301 is able to calculatethe least square sum of errors, which is the error value S, by thecalculation corresponding to equation (63) based on the mixture-ratiorelated information containing j, k, m, q, p, s, t, and u correspondingto the estimated mixture ratio calculated by the model of the coveredbackground area and the estimated mixture ratio calculated by the modelof the covered background area. $\begin{matrix}{S = {\sum\limits_{x,y}\left\{ {M - \left\lbrack {{\left( {{jm} + {kq} + p} \right) \cdot B} + {j \cdot s} + {k \cdot t} + u} \right\rbrack} \right\}^{2}}} & (63)\end{matrix}$

[0434] The predictive-error calculating portion 302 is able to calculatethe error value for each pixel by the calculation corresponding toequation (63) based on the mixture-ratio related informationcorresponding to the estimated mixture ratio calculated by the model ofthe uncovered background area and the estimated mixture ratio calculatedby the model of the uncovered background area, and supplies thecalculated error value to the covered-background-area determiningportion 304.

[0435] The uncovered-background-area determining portion 303 determinesfor each pixel whether the error value supplied from thepredictive-error calculating portion 301 is greater than or equal to theprestored threshold Th. If it is determined that the error value isgreater than or equal to the prestored threshold Th, theuncovered-background-area determining portion 303 determines that thedesignated pixel belongs to the uncovered background area, and sets aflag indicating the uncovered background area in correspondence with thedesignated pixel. The uncovered-background-area determining portion 303supplies the flag indicating the uncovered background area, which is setfor each pixel, to the synthesizer 306.

[0436] The covered-background-area determining portion 304 determinesfor each pixel whether the error value supplied from thepredictive-error calculating portion 302 is greater than or equal to theprestored threshold Th. If it is determined that the error value isgreater than or equal to the prestored threshold Th, thecovered-background-area determining portion 304 determines that thedesignated pixel belongs to the covered background area, and sets a flagindicating the covered background area in correspondence with thedesignated pixel. The covered-background-area determining portion 304supplies the flag indicating the covered background area, which is setfor each pixel, to the synthesizer 306.

[0437] The foreground/background area determining portion 305 determineswhether each pixel belongs to the foreground area or the backgroundarea, and supplies a flag indicating the foreground area and a flagindicating the background area, the flag being set for each pixel, tothe synthesizer 306.

[0438] The synthesizer 306 synthesizes area information indicating oneof the uncovered background area, the covered background area, theforeground area, and the background area for each pixel based on theflag indicating the uncovered background area supplied from theuncovered-background-area determining portion 303, the flag indicatingthe covered background area supplied from the covered-background-areadetermining portion 304, and the flag indicating the foreground area andthe flag indicating the background area supplied from theforeground/background area determining portion 305. The synthesizer 306supplies the synthesized area information to the mixture-ratiodetermining portion 307, and also outputs the area information.

[0439] The mixture-ratio determining portion 307 determines the mixtureratio α based on the area information supplied from the synthesizer 306.

[0440] As described above, the area specifying unit 104 is able togenerate area information based on the estimated mixture ratio and themixture-ratio related information in correspondence with the method forestimating the mixture ratio by the mixture-ratio calculator 103.

[0441]FIG. 44 is a block diagram illustrating the configuration of thearea specifying unit 104 for specifying the area based on the mixtureratios estimated for each component signal, the correspondingmixture-ratio related information, and the input image, which is inputas the component signal. The elements similar to those shown in FIG. 35are indicated by like reference numerals, and an explanation thereof isthus omitted.

[0442] A predictive-error calculating portion 301-1 calculates the errorvalue for each pixel based on the mixture-ratio related informationcorresponding to the estimated mixture ratio calculated by a model ofthe covered background area and the estimated mixture ratio calculatedby a model of the covered background area, the estimated mixture ratiosbeing calculated from component 1 of the input image, and supplies thecalculated error value to an adder 321.

[0443] A predictive-error calculating portion 301-2 calculates the errorvalue for each pixel based on the mixture-ratio related informationcorresponding to the estimated mixture ratio calculated by a model ofthe covered background area and the estimated mixture ratio calculatedby a model of the covered background area, the estimated mixture ratiosbeing calculated from component 2 of the input image, and supplies thecalculated error value to the adder 321.

[0444] A predictive-error calculating portion 301-3 calculates the errorvalue for each pixel based on the mixture-ratio related informationcorresponding to the estimated mixture ratio calculated by a model ofthe covered background area and the estimated mixture ratio calculatedby a model of the covered background area, the estimated mixture ratiosbeing calculated from component 3 of the input image, and supplies thecalculated error value to the adder 321.

[0445] A predictive-error calculating portion 302-1 calculates the errorvalue for each pixel based on the mixture-ratio related informationcorresponding to the estimated mixture ratio calculated by a model ofthe uncovered background area and the estimated mixture ratio calculatedby a model of the uncovered background area, the estimated mixtureratios being calculated from component 1 of the input image, andsupplies the calculated error value to an adder 322.

[0446] A predictive-error calculating portion 302-2 calculates the errorvalue for each pixel based on the mixture-ratio related informationcorresponding to the estimated mixture ratio calculated by a model ofthe uncovered background area and the estimated mixture ratio calculatedby a model of the uncovered background area, the estimated mixtureratios being calculated from component 2 of the input image, andsupplies the calculated error value to the adder 322.

[0447] A predictive-error calculating portion 302-3 calculates the errorvalue for each pixel based on the mixture-ratio related informationcorresponding to the estimated mixture ratio calculated by a model ofthe uncovered background area and the estimated mixture ratio calculatedby a model of the uncovered background area, the estimated mixtureratios being calculated from component 3 of the input image, andsupplies the calculated error value to the adder 322.

[0448] The adder 321 adds the error value supplied from thepredictive-error calculating portion 301-1, the error value suppliedfrom the predictive-error calculating portion 301-2, and the error valuesupplied from the predictive-error calculating portion 301-3, andsupplies the added error value to the uncovered-background-areadetermining portion 303.

[0449] The adder 322 adds the error value supplied from thepredictive-error calculating portion 302-1, the error value suppliedfrom the predictive-error calculating portion 302-2, and the error valuesupplied from the predictive-error calculating portion 302-3, andsupplies the added error value to the covered-background-areadetermining portion 304.

[0450] An adder 323 adds component 1 of the input image, component 2 ofthe input image, and component 3 of the input image, and supplies addedcomponent 1, component 2, and component 3 to the foreground/backgroundarea determining portion 305.

[0451] The uncovered-background-area determining portion 303 determinesfor each pixel whether the error value supplied from the adder 321 isgreater than or equal to the prestored threshold Th. If it is determinedthat the error value is greater than or equal to the threshold Th, theuncovered-background-area determining portion 303 determines that thedesignated pixel belongs to the uncovered background area, and sets aflag indicating the uncovered background area in correspondence with thedesignated pixel. The uncovered-background-area determining portion 303supplies the flag indicating the uncovered background area, which is setfor each pixel, to the synthesizer 306.

[0452] The covered-background-area determining portion 304 determinesfor each pixel whether the error value supplied from the adder 322 isgreater than or equal to the prestored threshold Th. If it is determinedthat the error value is greater than or equal to the threshold Th, thecovered-background-area determining portion 304 determines that thedesignated pixel belongs to the covered background area, and sets a flagindicating the covered background area in correspondence with thedesignated pixel. The covered-background-area determining portion 304supplies the flag indicating the covered background area, which is setfor each pixel, to the synthesizer 306.

[0453] The foreground/background area determining portion 305 determinesbased on the added component 1, component 2, and component 3 whethereach pixel belongs to the foreground area or the background area, andsupplies a flag indicating the foreground area and a flag indicating thebackground area, which are set for each pixel, to the synthesizer 306.

[0454] The synthesizer 306 synthesizes area information indicating oneof the uncovered background area, the covered background area, theforeground area, and the background area based on the flag indicatingthe uncovered background area supplied from theuncovered-background-area determining portion 303, the flag indicatingthe covered background area supplied from the covered-background-areadetermining portion 304, and the flag indicating the foreground area andthe flag indicating the background area supplied from theforeground/background area determining portion 305. The synthesizer 306supplies the synthesized area information to the mixture-ratiodetermining portion 307, and also outputs the area information.

[0455] As described above, the area specifying unit 104 shown in FIG. 44is able to specify the area based on the mixture ratio estimated foreach component signal and the corresponding mixture-ratio relatedinformation, and the input image, which is input as the componentsignal. The area specifying unit 104 configured as shown in FIG. 44 isable to specify the area more precisely compared to the area specifyingunit 104 configured as shown in FIG. 35.

[0456]FIG. 45 is a block diagram illustrating another configuration ofthe area specifying unit 104 for specifying the area based on themixture ratio estimated for each component signal and the correspondingmixture-ratio related information, and the input signal, which is inputas the component signal.

[0457] The elements similar to those shown in FIG. 44 are designatedwith like reference numerals, and an explanation thereof is thusomitted.

[0458] The predictive-error calculating portion 301-1 calculates theerror value for each pixel based on the mixture-ratio relatedinformation corresponding to the estimated mixture ratio calculated by amodel of the covered background area and the estimated mixture ratiocalculated by a model of the covered background area, the estimatedmixture ratios being calculated from component 1 of the input image, andsupplies the calculated error value to an uncovered-background-areadetermining portion 303-1.

[0459] The predictive-error calculating portion 301-2 calculates theerror value for each pixel based on the mixture-ratio relatedinformation corresponding to the estimated mixture ratio calculated by amodel of the covered background area and the estimated mixture ratiocalculated by a model of the covered background area, the estimatedmixture ratios being calculated from component 2 of the input image, andsupplies the calculated error value to an uncovered-background-areadetermining portion 303-2.

[0460] The predictive-error calculating portion 301-3 calculates theerror value for each pixel based on the mixture-ratio relatedinformation corresponding to the estimated mixture ratio calculated by amodel of the covered background area and the estimated mixture ratiocalculated by a model of the covered background area, the estimatedmixture ratios being calculated from component 3 of the input image, andsupplies the calculated error value to an uncovered-background-areadetermining portion 303-3.

[0461] The predictive-error calculating portion 302-1 calculates theerror value for each pixel based on the mixture-ratio relatedinformation corresponding to the estimated mixture ratio calculated by amodel of the uncovered background area and the estimated mixture ratiocalculated by a model of the uncovered background area, the estimatedmixture ratios being calculated from component 1 of the input image, andsupplies the calculated error value to a covered-background-areadetermining portion 304-1.

[0462] The predictive-error calculating portion 302-2 calculates theerror value for each pixel based on the mixture-ratio relatedinformation corresponding to the estimated mixture ratio calculated by amodel of the uncovered background area and the estimated mixture ratiocalculated by a model of the uncovered background area, the estimatedmixture ratios being calculated from component 2 of the input image, andsupplies the calculated error value to a covered-background-areadetermining portion 304-2.

[0463] The predictive-error calculating portion 302-3 calculates theerror value for each pixel based on the mixture-ratio relatedinformation corresponding to the estimated mixture ratio calculated by amodel of the uncovered background area and the estimated mixture ratiocalculated by a model of the uncovered background area, the estimatedmixture ratios being calculated from component 3 of the input image, andsupplies the calculated error value to a covered-background-areadetermining portion 304-3.

[0464] The uncovered-background-area determining portion 303-1determines for each pixel whether the error value supplied from thepredictive-error calculating portion 301-1 is greater than or equal tothe prestored threshold Th. If it is determined that the error value isgreater than or equal to the threshold Th, the uncovered-background-areadetermining portion 303-1 determines that the designated pixel belongsto the uncovered background area, and sets a flag indicating theuncovered background area in correspondence with the designated pixel.The uncovered-background-area determining portion 303-1 supplies theflag indicating the uncovered background area, which is set for eachpixel, to a logical-OR calculating portion 341.

[0465] The uncovered-background-area determining portion 303-2determines for each pixel whether the error value supplied from thepredictive-error calculating portion 301-2 is greater than or equal tothe prestored threshold Th. If it is determined that the error value isgreater than or equal to the threshold Th, the uncovered-background-areadetermining portion 303-2 determines that the designated pixel belongsto the uncovered background area, and sets a flag indicating theuncovered background area in correspondence with the designated pixel.The uncovered-background-area determining portion 303-2 supplies theflag indicating the uncovered background area, which is set for eachpixel, to the logical-OR calculating portion 341.

[0466] The uncovered-background-area determining portion 303-3determines for each pixel whether the error value supplied from thepredictive-error calculating portion 301-3 is greater than or equal tothe prestored threshold Th. If it is determined that the error value isgreater than or equal to the threshold Th, the uncovered-background-areadetermining portion 303-3 determines that the designated pixel belongsto the uncovered background area, and sets a flag indicating theuncovered background area in correspondence with the designated pixel.The uncovered-background-area determining portion 303-3 supplies theflag indicating the uncovered background area, which is set for eachpixel, to the logical-OR calculating portion 341.

[0467] The covered-background-area determining portion 304-1 determinesfor each pixel whether the error value supplied from thepredictive-error calculating portion 302-1 is greater than or equal tothe prestored threshold Th. If it is determined that the error value isgreater than or equal to the threshold Th, the covered-background-areadetermining portion 304-1 determines that the designated pixel belongsto the covered background area, and sets a flag indicating the coveredbackground area in correspondence with the designated pixel. Thecovered-background-area determining portion 304-1 supplies the flagindicating the covered background area, which is set for each pixel, toa logical-OR calculating portion 342.

[0468] The covered-background-area determining portion 304-2 determinesfor each pixel whether the error value supplied from thepredictive-error calculating portion 302-2 is greater than or equal tothe prestored threshold Th. If it is determined that the error value isgreater than or equal to the threshold Th, the covered-background-areadetermining portion 304-2 determines that the designated pixel belongsto the covered background area, and sets a flag indicating the coveredbackground area in correspondence with the designated pixel. Thecovered-background-area determining portion 304-2 supplies the flagindicating the covered background area, which is set for each pixel, tothe logical-OR calculating portion 342.

[0469] The covered-background-area determining portion 304-3 determinesfor each pixel whether the error value supplied from thepredictive-error calculating portion 302-3 is greater than or equal tothe prestored threshold Th. If it is determined that the error value isgreater than or equal to the threshold Th, the covered-background-areadetermining portion 304-3 determines that the designated pixel belongsto the covered background area, and sets a flag indicating the coveredbackground area in correspondence with the designated pixel. Thecovered-background-area determining portion 304-3 supplies the flagindicating the covered background area, which is set for each pixel, tothe logical-OR calculating portion 342.

[0470] A foreground/background area determining portion 305-1 determinesbased on component 1 whether each pixel belongs to the foreground areaor the background area, and supplies a flag indicating the foregroundarea or a flag indicating the background area, which is set for eachpixel, to a logical-OR calculating portion 343.

[0471] A foreground/background area determining portion 305-2 determinesbased on component 2 whether each pixel belongs to the foreground areaor the background area, and supplies a flag indicating the foregroundarea or a flag indicating the background area, which is set for eachpixel, to the logical-OR calculating portion 343.

[0472] A foreground/background area determining portion 305-3 determinesbased on component 3 whether each pixel belongs to the foreground areaor the background area, and supplies a flag indicating the foregroundarea or a flag indicating the background area, which is set for eachpixel, to the logical-OR calculating portion 343.

[0473] The logical-OR calculating portion 341 calculates the logical ORof the uncovered background area indicated by the flag supplied from theuncovered-background-area determining portion 303-1, the uncoveredbackground area indicated by the flag supplied from theuncovered-background-area determining portion 303-2, and the uncoveredbackground area indicated by the flag supplied from theuncovered-background-area determining portion 303-3 based on the flagindicating the uncovered background area supplied from theuncovered-background-area determining portion 303-1, the flag indicatingthe uncovered background area supplied from theuncovered-background-area determining portion 303-2, and the flagindicating the uncovered background area supplied from theuncovered-background-area determining portion 303-3 so as to generate aflag indicating the uncovered background area calculated by the logicalOR. The logical-OR calculating portion 341 supplies the generated flagindicating the uncovered background area to the synthesizer 306.

[0474] The logical-OR calculating portion 342 calculates the logical ORof the covered background area indicated by the flag supplied from thecovered-background-area determining portion 304-1, the coveredbackground area indicated by the flag supplied from thecovered-background-area determining portion 304-2, and the coveredbackground area indicated by the flag supplied from thecovered-background-area determining portion 304-3 based on the flagindicating the covered background area supplied from thecovered-background-area determining portion 304-1, the flag indicatingthe covered background area supplied from the covered-background-areadetermining portion 304-2, and the flag indicating the coveredbackground area supplied from the covered-background-area determiningportion 304-3 so as to generate a flag indicating the covered backgroundarea calculated by the logical OR. The logical-OR calculating portion342 supplies the generated flag indicating the covered background areato the synthesizer 306.

[0475] The logical-OR calculating portion 343 calculates the logical ORof the foreground area indicated by the flag supplied from theforeground/background area determining portion 305-1, the foregroundarea indicated by the flag supplied from the foreground/background areadetermining portion 305-2, and the foreground area indicated by the flagsupplied from the foreground/background area determining portion 305-3based on the flag indicating the foreground area supplied from theforeground/background area determining portion 305-1, the flagindicating the foreground area supplied from the foreground/backgroundarea determining portion 305-2, and the flag indicating the foregroundarea supplied from the foreground/background area determining portion305-3 so as to generate a flag indicating the foreground area calculatedby the logical OR. The logical-OR calculating portion 343 supplies thegenerated flag indicating the foreground area to the synthesizer 306.

[0476] The logical-OR calculating portion 343 calculates the logical ORof the background area indicated by the flag supplied from theforeground/background area determining portion 305-1, the backgroundarea indicated by the flag supplied from the foreground/background areadetermining portion 305-2, and the background area indicated by the flagsupplied from the foreground/background area determining portion 305-3based on the flag indicating the background area supplied from theforeground/background area determining portion 305-1, the flagindicating the background area supplied from the foreground/backgroundarea determining portion 305-2, and the flag indicating the backgroundarea supplied from the foreground/background area determining portion305-3 so as to generate a flag indicating the background area calculatedby the logical OR. The logical-OR calculating portion 343 supplies thegenerated flag indicating the background area to the synthesizer 306.

[0477] The synthesizer 306 synthesizes area information indicating oneof the uncovered background area, the covered background area, theforeground area, and the background area for each pixel based on theflag indicating the uncovered background area supplied from thelogical-OR calculating portion 341, the flag indicating the coveredbackground area supplied from the logical-OR calculating portion 342,and the flag indicating the foreground area and the flag indicating thebackground area supplied from the logical-OR calculating portion 343.The synthesizer 306 outputs the synthesized area information.

[0478] The area specifying unit 104 configured as shown in FIG. 45 isable to output the area information that specifies the entirety of eachof the foreground area, the background area, the covered backgroundarea, and the uncovered background area.

[0479]FIG. 46 is a block diagram illustrating still anotherconfiguration of the area specifying unit 104 for specifying the areabased on the mixture ratio estimated for each component signal and thecorresponding mixture-ratio related information, and the input image,which is input as the component signal.

[0480] The elements similar to those shown in FIG. 45 are indicated bylike reference numerals, and an explanation thereof is thus omitted.

[0481] A logical-AND calculating portion 361 calculates the logical ANDof the uncovered background area indicated by the flag supplied from theuncovered-background-area determining portion 303-1, the uncoveredbackground area indicated by the flag supplied from theuncovered-background-area determining portion 303-2, and the uncoveredbackground area indicated by the flag supplied from theuncovered-background-area determining portion 303-3 based on the flagindicating the uncovered background area supplied from theuncovered-background-area determining portion 303-1, the flag indicatingthe uncovered background area supplied from theuncovered-background-area determining portion 303-2, and the flagindicating the uncovered background area supplied from theuncovered-background-area determining portion 303-3, and generates aflag indicating the uncovered background area calculated by the logicalAND. The logical-AND calculating portion 361 supplies the generated flagindicating the uncovered background area to the synthesizer 306.

[0482] A logical-AND calculating portion 362 calculates the logical ANDof the covered background area indicated by the flag supplied from thecovered-background-area determining portion 304-1, the coveredbackground area indicated by the flag supplied from thecovered-background-area determining portion 304-2, and the coveredbackground area indicated by the flag supplied from thecovered-background-area determining portion 304-3 based on the flagindicating the covered background area supplied from thecovered-background-area determining portion 304-1, the flag indicatingthe covered background area supplied from the covered-background-areadetermining portion 304-2, and the flag indicating the coveredbackground area supplied from the covered-background-area determiningportion 304-3, and generates a flag indicating the covered backgroundarea calculated by the logical AND. The logical-AND calculating portion362 supplies the generated flag indicating the covered background areato the synthesizer 306.

[0483] A logical-AND calculating portion 363 calculates the logical ANDof the foreground area indicated by the flag supplied from theforeground/background area determining portion 305-1, the foregroundarea indicated by the flag supplied from the foreground/background areadetermining portion 305-2, and the foreground area indicated by the flagsupplied from the foreground/background area determining portion 305-3based on the flag indicating the foreground area supplied from theforeground/background area determining portion 305-1, the flagindicating the foreground area supplied from the foreground/backgroundarea determining portion 305-2, and the flag indicating the foregroundarea supplied from the foreground/background area determining portion305-3, and generates a flag indicating the foreground area calculated bythe logical AND. The logical-AND calculating portion 363 supplies thegenerated flag indicating the foreground area to the synthesizer 306.

[0484] The logical-AND calculating portion 363 calculates the logicalAND of the background area indicated by the flag supplied from theforeground/background area determining portion 305-1, the backgroundarea indicated by the flag supplied from the foreground/background areadetermining portion 305-2, and the background area indicated by the flagsupplied from the foreground/background area determining portion 305-3based on the flag indicating the background area supplied from theforeground/background area determining portion 305-1, the flagindicating the background area supplied from the foreground/backgroundarea determining portion 305-2, and the flag indicating the backgroundarea supplied from the foreground/background area determining portion305-3, and generates a flag indicating the background area calculated bythe logical AND. The logical-AND calculating portion 363 supplies thegenerated flag indicating the background area to the synthesizer 306.

[0485] The synthesizer 306 synthesizes area information indicating oneof the uncovered background area, the covered background area, theforeground area, and the background area for each pixel based on theflag indicating the uncovered background area supplied from the logicalAND calculating portion 361, the flag indicating the covered backgroundarea supplied from the logical AND calculating portion 362, and the flagindicating the foreground area and the flag indicating the backgroundarea supplied from the logical AND calculating portion 363. Thesynthesizer 306 outputs the synthesized area information.

[0486] The area specifying unit 104 configured as shown in FIG. 46 isable to output area information having small errors.

[0487] The area specifying processing performed by the area specifyingunit 104 is described below with reference to the flowchart of FIG. 47.In step S301, the area specifying unit 104 performs processing forspecifying the covered background area for each pixel based on the errorvalue. Details of the covered-background-area specifying processing aregiven below.

[0488] In step S302, the area specifying unit 104 performs processingfor specifying the uncovered background area for each pixel based on theerror value. Details of the uncovered-background-area specifyingprocessing are given below.

[0489] In step S303, the foreground/background area determining portion305 specifies the foreground or the background for each pixel, and theprocessing is completed.

[0490] The covered-background-area specifying processing correspondingto step S301 is discussed below with reference to the flowchart of FIG.48.

[0491] In step S321, the predictive-error calculating portion 302calculates the error value by using a model corresponding to theuncovered background area. The predictive-error calculating portion 302supplies the calculated error value to the covered-background-areadetermining portion 304.

[0492] In step S322, the covered-background-area determining portion 304determines whether the error value supplied from the predictive-errorcalculating portion 302 is greater than or equal to the threshold Th. Ifit is determined that the error value is greater than or equal to thethreshold Th, the process proceeds to step S323. In step S323, thepredictive-error calculating portion 302 sets the flag indicating thecovered background area in the pixel having the error value. The processthen proceeds to step S324.

[0493] If it is determined in step S322 that the error value is notgreater than or equal to the threshold Th, it can be proved that thepixel does not belong to the covered background area. Accordingly, theprocessing of step S323 is skipped, and the process proceeds to stepS324.

[0494] In step S324, the area specifying unit 104 determines whether theprocessing has been performed for the whole screen. If it is determinedthat the processing has not been performed for the whole screen, theprocess returns to step S321, and the covered-background-areadetermining processing is repeated.

[0495] If it is determined in step S324 that the processing has beenperformed for the whole screen, the process proceeds to step S325 inwhich the covered-background-area determining portion 304 outputs a flagindicating the covered background area. The processing is thencompleted.

[0496] The uncovered-background-area specifying processing correspondingto step S302 is discussed below with reference to the flowchart of FIG.49.

[0497] In step S341, the predictive-error calculating portion 301calculates the error value by using a model corresponding to the coveredbackground area. The predictive-error calculating portion 301 suppliesthe calculated error value to the uncovered-background-area determiningportion 303.

[0498] In step S342, the uncovered-background-area determining portion303 determines whether the error value supplied from thepredictive-error calculating portion 301 is greater than or equal to thethreshold Th. If it is determined that the error value is greater thanor equal to the threshold Th, the process proceeds to step S343. In stepS343, the flag indicating the uncovered background area is set in thepixel having the error value. The process then proceeds to step S344.

[0499] If it is determined in step S342 that the error value is notgreater than or equal to the threshold Th, it can be proved that thepixel does not belong to the uncovered background area. Accordingly, theprocessing of step S343 is skipped, and the process proceeds to stepS344.

[0500] In step S344, the area specifying unit 104 determines whether theprocessing has been performed for the whole screen. If it is determinedthat the processing has not been performed for the whole screen, theprocess returns to step S341, and the uncovered-background-areadetermining processing is repeated.

[0501] If it is determined in step S344 that the processing has beenperformed for the whole screen, the process proceeds to step S345 inwhich the uncovered-background-area determining portion 303 outputs aflag indicating the uncovered background area. The processing is thencompleted.

[0502] As discussed above, the area specifying unit 104 is able tocalculate the error value based on the estimated mixture ratio and themixture-ratio related information corresponding to the estimated mixtureratio so as to specify the covered background area and the uncoveredbackground area based on the calculated error value.

[0503] The area specifying unit 104 is able to determine the mixtureratio α based on the generated area information, and outputs thedetermined mixture ratio α.

[0504] By utilizing the mixture ratio α, it is possible to separate theforeground components and the background components contained in a pixelvalue while maintaining the information of motion blur contained in theimage corresponding to the moving object.

[0505] The area specifying unit 104 configured as shown in FIG. 44specifies the area according to processing similar to that describedwith reference to the flowcharts of FIGS. 47 through 49, except that thecovered background area or the uncovered background area is specifiedbased on the added error values. A detailed explanation of theprocessing is thus omitted.

[0506] The area specifying unit 104 configured as shown in FIG. 45specifies the area according to processing similar to that describedwith reference to the flowcharts of FIGS. 47 through 49, except that thearea is specified for each component, and the final area is determinedby the logical OR of the specified areas. A detailed explanation of theprocessing is thus omitted.

[0507] The area specifying unit 104 configured as shown in FIG. 46specifies the area according to processing similar to that describedwith reference to the flowcharts of FIGS. 47 through 49, except that thearea is specified for each component, and the final area is determinedby the logical AND of the specified areas. A detailed explanation of theprocessing is thus omitted.

[0508] The foreground/background separator 105 is discussed below. FIG.50 is a block diagram illustrating an example of the configuration ofthe foreground/background separator 105. The input image supplied to theforeground/background separator 105 is supplied to a separating portion601, a switch 602, and a switch 604. The area information supplied fromthe area specifying unit 104 and indicating the information of thecovered background area and the uncovered background area is supplied tothe separating portion 601. The area information indicating theforeground area is supplied to the switch 602. The area informationindicating the background area supplied to the switch 604.

[0509] The mixture ratio α supplied from the mixture-ratio calculator103 is supplied to the separating portion 601.

[0510] The separating portion 601 separates the foreground componentsfrom the input image based on the area information indicating thecovered background area, the area information indicating the uncoveredbackground area, and the mixture ratio α, and supplies the separatedforeground components to a synthesizer 603. The separating portion 601also separates the background components from the input image, andsupplies the separated background components to a synthesizer 605.

[0511] The switch 602 is closed when a pixel corresponding to theforeground is input based on the area information indicating theforeground area, and supplies only the pixels corresponding to theforeground contained in the input image to the synthesizer 603.

[0512] The switch 604 is closed when a pixel corresponding to thebackground is input based on the area information indicating thebackground area, and supplies only the pixels corresponding to thebackground contained in the input image to the synthesizer 605.

[0513] The synthesizer 603 synthesizes a foreground component imagebased on the foreground components supplied from the separating portion601 and the pixels corresponding to the foreground supplied from theswitch 602, and outputs the synthesized foreground component image.Since the foreground area and the mixed area do not overlap, thesynthesizer 603 applies, for example, logical OR to the foregroundcomponents and the foreground pixels, thereby synthesizing theforeground component image.

[0514] In the initializing processing executed at the start of thesynthesizing processing for the foreground component image, thesynthesizer 603 stores an image whose pixel values are all 0 in abuilt-in frame memory. Then, in the synthesizing processing for theforeground component image, the synthesizer 603 stores the foregroundcomponent image (overwrites the previous image by the foregroundcomponent image). Accordingly, 0 is stored in the pixels correspondingto the background area in the foreground component image output from thesynthesizer 603.

[0515] The synthesizer 605 synthesizes a background component imagebased on the background components supplied from the separating portion601 and the pixels corresponding to the background supplied from theswitch 604, and outputs the synthesized background component image.Since the background area and the mixed area do not overlap, thesynthesizer 605 applies, for example, logical OR to the backgroundcomponents and the background pixels, thereby synthesizing thebackground component image.

[0516] In the initializing processing executed at the start of thesynthesizing processing for the background component image, thesynthesizer 605 stores an image whose pixel values are all 0 in abuilt-in frame memory. Then, in the synthesizing processing for thebackground component image, the synthesizer 605 stores the backgroundcomponent image (overwrites the previous image by the backgroundcomponent image). Accordingly, 0 is stored in the pixels correspondingto the foreground area in the background component image output from thesynthesizer 605.

[0517]FIG. 51A illustrates the input image input into theforeground/background separator 105 and the foreground component imageand the background component image output from the foreground/backgroundseparator 105. FIG. 51B illustrates a model corresponding to the inputimage input into the foreground/background separator 105 and theforeground component image and the background component image outputfrom the foreground/background separator 105.

[0518]FIG. 51A is a schematic diagram illustrating the image to bedisplayed, and FIG. 51B is a model obtained by expanding in the timedirection the pixels disposed in one line including the pixels belongingto the foreground area, the pixels belonging to the background area, andthe pixels belonging to the mixed area corresponding to FIG. 51A.

[0519] As shown in FIGS. 51A and 51B, the background component imageoutput from the foreground/background separator 105 consists of thepixels belonging to the background area and the background componentscontained in the pixels of the mixed area.

[0520] As shown in FIGS. 51A and 51B, the foreground component imageoutput from the foreground/background separator 105 consists of thepixel belonging to the foreground area and the foreground componentscontained in the pixels of the mixed area.

[0521] The pixel values of the pixels in the mixed area are separatedinto the background components and the foreground components by theforeground/background separator 105. The separated background componentsform the background component image together with the pixels belongingto the background area. The separated foreground components form theforeground component image together with the pixels belonging to theforeground area.

[0522] As discussed above, in the foreground component image, the pixelvalues of the pixels corresponding to the background area are set to 0,and significant pixel values are set in the pixels corresponding to theforeground area and the pixels corresponding to the mixed area.Similarly, in the background component image, the pixel values of thepixels corresponding to the foreground area are set to 0, andsignificant pixel values are set in the pixels corresponding to thebackground area and the pixels corresponding to the mixed area.

[0523] A description is given below of the processing executed by theseparating portion 601 for separating the foreground components and thebackground components from the pixels belonging to the mixed area.

[0524]FIG. 52 illustrates a model of an image indicating foregroundcomponents and background components in two frames including aforeground object moving from the left to the right in FIG. 52. In themodel of the image shown in FIG. 52, the amount of movement v is 4, andthe number of virtual divided portions is 4.

[0525] In frame #n, the leftmost pixel and the fourteenth througheighteenth pixels from the left consist of only the backgroundcomponents and belong to the background area. In frame #n, the secondthrough fourth pixels from the left contain the background componentsand the foreground components, and belong to the uncovered backgroundarea. In frame #n, the eleventh through thirteenth pixels from the leftcontain background components and foreground components, and belong tothe covered background area. In frame #n, the fifth through tenth pixelsfrom the left consist of only the foreground components, and belong tothe foreground area.

[0526] In frame #n+1, the first through fifth pixels from the left andthe eighteenth pixel from the left consist of only the backgroundcomponents, and belong to the background area. In frame #n+1, the sixththrough eighth pixels from the left contain background components andforeground components, and belong to the uncovered background area. Inframe #n+1, the fifteenth through seventeenth pixels from the leftcontain background components and foreground components, and belong tothe covered background area. In frame #n+1, the ninth through fourteenthpixels from the left consist of only the foreground components, andbelong to the foreground area.

[0527]FIG. 53 illustrates the processing for separating the foregroundcomponents from the pixels belonging to the covered background area. InFIG. 53, α1 through α18 indicate mixture ratios of the individual pixelsof frame #n. In FIG. 53, the fifteenth through seventeenth pixels fromthe left belong to the covered background area.

[0528] The pixel value C15 of the fifteenth pixel from the left in frame#n can be expressed by equation (64): $\begin{matrix}\begin{matrix}{{C15} = {{{B15}/v} + {{F09}/v} + {{F08}/v} + {{F07}/v}}} \\{= {{\alpha \quad {15 \cdot {B15}}} + {{F09}/v} + {{F08}/v} + {{F07}/v}}} \\{= {{\alpha \quad {15 \cdot {P15}}} + {{F09}/v} + {{F08}/v} + {{F07}/v}}}\end{matrix} & (64)\end{matrix}$

[0529] where α15 indicates the mixture ratio of the fifteenth pixel fromthe left in frame #n, and P15 designates the pixel value of thefifteenth pixel from the left in frame #n−1.

[0530] The sum f15 of the foreground components of the fifteenth pixelfrom the left in frame #n can be expressed by equation (65) based onequation (64). $\begin{matrix}\begin{matrix}{{f15} = {{{F09}/v} + {{F08}/v} + {{F07}/v}}} \\{= {{C15} - {\alpha \quad {15 \cdot {P15}}}}}\end{matrix} & (65)\end{matrix}$

[0531] Similarly, the sum f16 of the foreground components of thesixteenth pixel from the left in frame #n can be expressed by equation(66), and the sum f17 of the foreground components of the seventeenthpixel from the left in frame #n can be expressed by equation (67).

f16=C16−α16·P16   (66)

f17=C17−α17·P17   (67)

[0532] In this manner, the foreground components fc contained in thepixel value C of the pixel belonging to the covered background area canbe expressed by equation (68)

fc=C−α·P   (68)

[0533] where P designates the pixel value of the corresponding pixel inthe previous frame.

[0534]FIG. 54 illustrates the processing for separating the foregroundcomponents from the pixels belonging to the uncovered background area.In FIG. 54, α1 through α18 indicate mixture ratios of the individualpixels of frame #n. In FIG. 54, the second through fourth pixels fromthe left belong to the uncovered background area.

[0535] The pixel value C02 of the second pixel from the left in frame #ncan be expressed by equation (69): $\begin{matrix}\begin{matrix}{{C02} = {{{B02}/v} + {{B02}/v} + {{B02}/v} + {{F01}/v}}} \\{= {{\alpha \quad {2 \cdot {B02}}} + {{F01}/v}}} \\{= {{\alpha \quad {2 \cdot {N02}}} + {{F01}/v}}}\end{matrix} & (69)\end{matrix}$

[0536] where α2 indicates the mixture ratio of the second pixel from theleft in frame #n, and N02 designates the pixel value of the second pixelfrom the left in frame #n+1.

[0537] The sum f02 of the foreground components of the second pixel fromthe left in frame #n can be expressed by equation (70) based on equation(69). $\begin{matrix}\begin{matrix}{{f02} = {{F01}/v}} \\{= {{C02} - {\alpha \quad {2 \cdot {N02}}}}}\end{matrix} & (70)\end{matrix}$

[0538] Similarly, the sum f03 of the foreground components of the thirdpixel from the left in frame #n can be expressed by equation (71), andthe sum f04 of the foreground components of the fourth pixel from theleft in frame #n can be expressed by equation (72).

f03=C03−α3·N03   (71)

f04=C04−α4·N04   (72)

[0539] In this manner, the foreground components fu contained in thepixel value C of the pixel belonging to the uncovered background areacan be expressed by equation (73):

fu=C−α·N   (73)

[0540] where N designates the pixel value of the corresponding pixel inthe subsequent frame.

[0541] As discussed above, the separating portion 601 is able toseparate the foreground components from the pixels belonging to themixed area and the background components from the pixels belonging tothe mixed area based on the information indicating the coveredbackground area and the information indicating the uncovered backgroundarea contained in the area information, and the mixture ratio α for eachpixel.

[0542]FIG. 55 is a block diagram illustrating an example of theconfiguration of the separating portion 601 for executing theabove-described processing. An image input into the separating portion601.is supplied to a frame memory 621, and the area informationindicating the covered background area and the uncovered background areasupplied from the mixture-ratio calculator 103 and the mixture ratio αare supplied to a separation processing block 622.

[0543] The frame memory 621 stores the input images in units of frames.When a frame to be processed is frame #n, the frame memory 621 storesframe #n−1, which is the frame one frame before frame #n, frame #n, andframe #n+1, which is the frame one frame after frame #n.

[0544] The frame memory 621 supplies the corresponding pixels in frame#n−1, frame #n, and frame #n+1 to the separation processing block 622.

[0545] The separation processing block 622 applies the calculationsdiscussed with reference to FIGS. 53 and 54 to the pixel values of thecorresponding pixels in frame #n−1, frame #n, and frame #n+1 suppliedfrom the frame memory 621 based on the area information indicating thecovered background area and the uncovered background area and themixture ratio α so as to separate the foreground components and thebackground components from the pixels belonging to the mixed area inframe #n, and supplies them to a frame memory 623.

[0546] The separation processing block 622 is formed of an uncoveredarea processor 631, a covered area processor 632, a synthesizer 633, anda synthesizer 634.

[0547] A multiplier 641 of the uncovered area processor 631 multipliesthe pixel value of the pixel in frame #n+1 supplied from the framememory 621 by the mixture ratio α, and outputs the resulting pixel valueto a switch 642. The switch 642 is closed when the pixel of frame #n(corresponding to the pixel in frame #n+1) supplied from the framememory 621 belongs to the uncovered background area, and supplies thepixel value multiplied by the mixture ratio α supplied from themultiplier 641 to a calculator 643 and the synthesizer 634. The valueobtained by multiplying the pixel value of the pixel in frame #n+1 bythe mixture ratio α output from the switch 642 is equivalent to thebackground components of the pixel value of the corresponding pixel inframe #n.

[0548] The calculator 643 subtracts the background components suppliedfrom the switch 642 from the pixel value of the pixel in frame #nsupplied from the frame memory 621 so as to obtain the foregroundcomponents. The calculator 643 supplies the foreground components of thepixel in frame #n belonging to the uncovered background area to thesynthesizer 633.

[0549] A multiplier 651 of the covered area processor 632 multiplies thepixel value of the pixel in frame #n−1 supplied from the frame memory621 by the mixture ratio α, and outputs the resulting pixel value to aswitch 652. The switch 652 is closed when the pixel of frame #n(corresponding to the pixel in frame #n−1) supplied from the framememory 621 belongs to the covered background area, and supplies thepixel value multiplied by the mixture ratio α supplied from themultiplier 651 to a calculator 653 and the synthesizer 634. The valueobtained by multiplying the pixel value of the pixel in frame #n−1 bythe mixture ratio α output from the switch 652 is equivalent to thebackground components of the pixel value of the corresponding pixel inframe #n.

[0550] The calculator 653 subtracts the background components suppliedfrom the switch 652 from the pixel value of the pixel in frame #nsupplied from the frame memory 621 so as to obtain the foregroundcomponents. The calculator 653 supplies the foreground components of thepixel in frame #n belonging to the covered background area to thesynthesizer 633.

[0551] The synthesizer 633 combines the foreground components of thepixels of frame #n belonging to the uncovered background area andsupplied from the calculator 643 with the foreground components of thepixels of frame #n belonging to the covered background area and suppliedfrom the calculator 653, and supplies the synthesized foregroundcomponents to the frame memory 623.

[0552] The synthesizer 634 combines the background components of thepixels of frame #n belonging to the uncovered background area andsupplied from the switch 642 with the background components of thepixels of frame #n belonging to the covered background area and suppliedfrom the switch 652, and supplies the synthesized background componentsto the frame memory 623.

[0553] The frame memory 623 stores the foreground components and thebackground components of the pixels in the mixed area of frame #nsupplied from the separation processing block 622.

[0554] The frame memory 623 outputs the stored foreground components ofthe pixels in the mixed area in frame #n and the stored backgroundcomponents of the pixels in the mixed area in frame #n.

[0555] By utilizing the mixture ratio α, which indicates the featurequantity, the foreground components and the background componentscontained in the pixel values can be completely separated.

[0556] The synthesizer 603 combines the foreground components of thepixels in the mixed area in frame #n output from the separating portion601 with the pixels belonging to the foreground area so as to generate aforeground component image. The synthesizer 605 combines the backgroundcomponents of the pixels in the mixed area in frame #n output from theseparating portion 601 with the pixels belonging to the background areaso as to generate a background component image.

[0557]FIG. 56A illustrates an example of the foreground component imagecorresponding to frame #n in FIG. 52. The leftmost pixel and thefourteenth pixel from the left consist of only the background componentsbefore the foreground and the background are separated, and thus, thepixel values are set to 0.

[0558] The second and fourth pixels from the left belong to theuncovered background area before the foreground and the background areseparated. Accordingly, the background components are set to 0, and theforeground components are maintained. The eleventh through thirteenthpixels from the left belong to the covered background area before theforeground and the background are separated. Accordingly, the backgroundcomponents are set to 0, and the foreground components are maintained.The fifth through tenth pixels from the left consist of only theforeground components, which are thus maintained.

[0559]FIG. 56B illustrates an example of the background component imagecorresponding to frame #n in FIG. 52. The leftmost pixel and thefourteenth pixel from the left consist of only the background componentsbefore the foreground and the background are separated, and thus, thebackground components are maintained.

[0560] The second through fourth pixels from the left belong to theuncovered background area before the foreground and the background areseparated. Accordingly, the foreground components are set to 0, and thebackground components are maintained. The eleventh through thirteenthpixels from the left belong to the covered background area before theforeground and the background are separated. Accordingly, the foregroundcomponents are set to 0, and the background components are maintained.The fifth through tenth pixels from the left consist of only theforeground components, and thus, the pixel values are set to 0.

[0561] The processing for separating the foreground and the backgroundexecuted by the foreground/background separator 105 is described belowwith reference to the flowchart of FIG. 57. In step S601, the framememory 621 of the separating portion 601 obtains an input image, andstores frame #n for which the foreground and the background areseparated together with the previous frame #n−1 and the subsequent frame#n+1.

[0562] In step S602, the separation processing block 622 of theseparating portion 601 obtains area information supplied from themixture-ratio calculator 103. In step S603, the separation processingblock 622 of the separating portion 601 obtains the mixture ratio αsupplied from the mixture-ratio calculator 103.

[0563] In step S604, the uncovered area processor 631 extracts thebackground components from the pixel values of the pixels belonging tothe uncovered background area supplied from the frame memory 621 basedon the area information and the mixture ratio α.

[0564] In step S605, the uncovered area processor 631 extracts theforeground components from the pixel values of the pixels belonging tothe uncovered background area supplied from the frame memory 621 basedon the area information and the mixture ratio α.

[0565] In step S606, the covered area processor 632 extracts thebackground components from the pixel values of the pixels belonging tothe covered background area supplied from the frame memory 621 based onthe area information and the mixture ratio α.

[0566] In step S607, the covered area processor 632 extracts theforeground components from the pixel values of the pixels belonging tothe covered background area supplied from the frame memory 621 based onthe area information and the mixture ratio α.

[0567] In step S608, the synthesizer 633 combines the foregroundcomponents of the pixels belonging to the uncovered background areaextracted in the processing of step S605 with the foreground componentsof the pixels belonging to the covered background area extracted in theprocessing of step S607. The synthesized foreground components aresupplied to the synthesizer 603. The synthesizer 603 further combinesthe pixels belonging to the foreground area supplied via the switch 602with the foreground components supplied from the separating portion 601so as to generate a foreground component image.

[0568] In step S609, the synthesizer 634 combines the backgroundcomponents of the pixels belonging to the uncovered background areaextracted in the processing of step S604 with the background componentsof the pixels belonging to the covered background area extracted in theprocessing of step S606. The synthesized background components aresupplied to the synthesizer 605. The synthesizer 605 further combinesthe pixels belonging to the background area supplied via the switch 604with the background components supplied from the separating portion 601so as to generate a background component image.

[0569] In step S610, the synthesizer 603 outputs the foregroundcomponent image. In step S611, the synthesizer 605 outputs thebackground component image. The processing is then completed.

[0570] As discussed above, the foreground/background separator 105 isable to separate the foreground components and the background componentsfrom the input image based on the area information and the mixture ratioα, and outputs the foreground component image consisting of only theforeground components and the background component image consisting ofonly the background components.

[0571] Adjustments of the amount of motion blur from a foregroundcomponent image are described below.

[0572]FIG. 58 is a block diagram illustrating an example of theconfiguration of the motion-blur adjusting unit 106. The motion vectorand the positional information thereof supplied from the motion detector102 are supplied to a unit-of-processing determining portion 801, amodel-forming portion 802, and a calculator 805. The area informationsupplied from the area specifying unit 104 is supplied to theunit-of-processing determining portion 801. The foreground componentimage supplied from the foreground/background separator 105 is suppliedto the adder 804.

[0573] The unit-of-processing determining portion 801 generates the unitof processing based on the motion vector and the positional informationthereof, and the area information, and supplies the generated unit ofprocessing to the model-forming portion 802 and the adder 804.

[0574] As indicated by A in FIG. 59, for example, the unit of processinggenerated by the unit-of-processing determining portion 801 indicatesconsecutive pixels disposed in the moving direction starting from thepixel corresponding to the covered background area of the foregroundcomponent image until the pixel corresponding to the uncoveredbackground area, or indicates consecutive pixels disposed in the movingdirection starting from the pixel corresponding to the uncoveredbackground area until the pixel corresponding to the covered backgroundarea. The unit of processing is formed of two pieces of data whichindicate, for example, the upper left point (which is the position ofthe leftmost or the topmost pixel in the image designated by the unit ofprocessing) and the lower right point.

[0575] The model-forming portion 802 forms a model based on the motionvector and the input unit of processing. More specifically, for example,the model-forming portion 802 may store in advance a plurality of modelsin accordance with the number of pixels contained in the unit ofprocessing, the number of virtual divided portions of the pixel value inthe time direction, and the number of foreground components for eachpixel. The model-forming portion 802 may then select the model in whichthe correlation between the pixel values and the foreground componentsis designated, such as that in FIG. 60, based on the unit of processingand the number of virtual divided portions of the pixel value in thetime direction.

[0576] It is now assumed, for example, that the number of pixelscorresponding to the unit of processing is 12, and that the amount ofmovement v within the shutter time is 5. Then, the model-forming portion802 sets the number of virtual divided portions to 5, and selects amodel formed of eight types of foreground components so that theleftmost pixel contains one foreground component, the second pixel fromthe left contains two foreground components, the third pixel from theleft contains three foreground components, the fourth pixel from theleft contains four pixel components, the fifth pixel from the leftcontains five foreground components, the sixth pixel from the leftcontains five foreground components, the seventh pixel from the leftcontains five foreground components, the eighth pixel from the leftcontains five foreground components, the ninth pixel from the leftcontains four foreground components, the tenth pixel from the leftcontains three foreground components, the eleventh pixel from the leftcontains two foreground components, and the twelfth pixel from the leftcontains one foreground component.

[0577] Instead of selecting a model from the prestored models, themodel-forming portion 802 may generate a model based on the motionvector and the unit of processing when the motion vector and the unit ofprocessing are supplied.

[0578] The model-forming portion 802 supplies the selected model to anequation generator 803.

[0579] The equation generator 803 generates an equation based on themodel supplied from the model-forming portion 802. A description isgiven below, with reference to the model of the foreground componentimage shown in FIG. 60, of equations generated by the equation generator803 when the number of foreground components is 8, the number of pixelscorresponding to the unit of processing is 12, and the amount ofmovement v is 5.

[0580] When the foreground components contained in the foregroundcomponent image corresponding to the shutter time/v are F01/v throughF08/v, the relationships between F01/v through F08/v and the pixelvalues C01 through C12 can be expressed by equations (74) through (85).

C01=F10/v   (74)

C02=F02/v+F01/v   (75)

C03=F03/v+F02/v+F01v   (76)

C04=F04/v+F03/v+F02/v+F01v   (77)

C05=F05/v+F04/v+F03/v+F02/v+F01 v   (78)

C06=F06/v+F05/v+F04/v+F03/v+F02/v   (79)

C07=F07/v+F06/v+F05/v+F04/v+F03/v   (80)

C08=F08/v+F07/v+F06/v+F05/v+F04/v   (81)

C09=F08/v+F07/v+F06/v+F05/v   (82)

C10=F08/v+F07/v+F06/v   (83)

C11=F08/v+F07/v   (84)

C12=F08/v   (85)

[0581] The equation generator 803 generates an equation by modifying thegenerated equations. The equations generated by the equation generator803 are indicated by equations (86) though (97).

C01=1·F01/v+0·F02/v+0·F03/v+0·F04/v+0·F05/v+0·F06/v+0·F07/v+0·F08/v  (86)

C02=1·F01/v+1·F02/v+0·F03/v+0·F04/v+0·F05/v+0·F06/v+0·F07/v+0·F08/v  (87)

C03=1·F01/v+1·F02/v+1·F03/v+0·F04/v+0·F05/v+0·F06/v+0·F07/v+0·F08/v  (88)

C04=1·F01/v+1·F02/v+1·F03/v+1·F04/v+0·F05/v+0·F06/v+0·F07/v+0·F08/v  (89)

C05=1·F10/v+1·F02/v+1·F03/v+1·F04/v+1·F05/v+0·F06/v+0·F07/v+0·F08/v  (90)

C06=0·F01/v+1·F02/v+1·F03/v+1·F04/v+1·F05/v+1·F06/v+0·F07/v+0·F08/v  (91)

C07=0·F01/v+1·F02/v+1·F03/v+1·F04/v+1·F05/v+0·F06/v+1·F07/v+1·F08/v  (92)

C08=0·F01/v+0·F02/v+0·F03/v+1·F04/v+1·F05/v+1·F06/v+1·F07/v+1·F08/v  (93)

C09=0·F01/v+0·F02/v+0·F03/v+0·F04/v+1·F05/v+1·F06/v+1·F07/v+1·F08/v  (94)

C10=0·F01/v+0·F02/v+0·F03/v+0·F04/v+0·F05/v+1·F06/v+1·F07/v+1·F08/v  (95)

C11=0·F01/v+0·F02/v+0·F03/v+0·F04/v+0·F05/v+0·F06/v+1·F07/v+1·F08/v  (96)

C12=0·F01/v+0·F02/v+0·F03/v+0·F04/v+0·F05/v+0·F06/v+0·F07/v+1·F08/v  (97)

[0582] Equations (86) through (97) can be expressed by equation (98).$\begin{matrix}{{Cj} = {\sum\limits_{i = 01}^{08}{{aij} \cdot {{Fi}/v}}}} & (98)\end{matrix}$

[0583] In equation (98), j designates the position of the pixel. In thisexample, j has one of the values from 1 to 12. In equation (98), idesignates the position of the foreground value. In this example, i hasone of the values from 1 to 8. In equation (98), aij has the value 0 or1 according to the values of i and j.

[0584] Equation (98) can be expressed by equation (99) in considerationof the error. $\begin{matrix}{{Cj} = {{\sum\limits_{i = 01}^{08}{{aij} \cdot {{Fi}/v}}} + {ej}}} & (99)\end{matrix}$

[0585] In equation (99), ej designates the error contained in thedesignated pixel Cj.

[0586] Equation (99) can be modified into equation (100).$\begin{matrix}{{ej} = {{Cj} - {\sum\limits_{i = 01}^{08}{{aij} \cdot {{Fi}/v}}}}} & (100)\end{matrix}$

[0587] In order to apply the method of least squares, the square sum Eof the error is defined as equation (101). $\begin{matrix}{E = {\sum\limits_{j = 01}^{12}{ej}^{2}}} & (101)\end{matrix}$

[0588] In order to minimize the error, the partial differential valueusing the variable Fk with respect to the square sum E of the errorshould be 0. Fk is determined so that equation (102) is satisfied.$\begin{matrix}\begin{matrix}{\frac{\partial E}{\partial{Fk}} = {2 \cdot {\sum\limits_{j = 01}^{12}{{ej} \cdot \frac{\partial{ej}}{\partial{Fk}}}}}} \\{= {2 \cdot {\sum\limits_{j = 01}^{12}\left\{ {{\left( {{Cj} - {\sum\limits_{i = 01}^{08}{{aij} \cdot {{Fi}/v}}}} \right) \cdot \left( {{- {akj}}/v} \right)} = 0} \right.}}}\end{matrix} & (102)\end{matrix}$

[0589] In equation (102), since the amount of movement v is a fixedvalue, equation (103) can be deduced. $\begin{matrix}{{\sum\limits_{j = 01}^{12}{{akj} \cdot \left( {{Cj} - {\sum\limits_{i = 01}^{08}{{aij} \cdot {{Fi}/v}}}} \right)}} = 0} & (103)\end{matrix}$

[0590] To expand equation (103) and transpose the terms, equation (104)can be obtained. $\begin{matrix}{{\sum\limits_{j = 01}^{12}\left( {{akj} \cdot {\sum\limits_{i = 01}^{08}{{aij} \cdot {Fi}}}} \right)} = {v\quad {\sum\limits_{j = 01}^{12}{{akj} \cdot {Cj}}}}} & (104)\end{matrix}$

[0591] Equation (104) is expanded into eight equations by substitutingthe individual integers from 1 to 8 into k in equation (104). Theobtained eight equations can be expressed by one matrix equation. Thisequation is referred to as a “normal equation”.

[0592] An example of the normal equation generated by the equationgenerator 803 based on the method of least squares is indicated byequation (105). $\begin{matrix}{{\begin{bmatrix}5 & 4 & 3 & 2 & 1 & 0 & 0 & 0 \\4 & 5 & 4 & 3 & 2 & 1 & 0 & 0 \\3 & 4 & 5 & 4 & 3 & 2 & 1 & 0 \\2 & 3 & 4 & 5 & 4 & 3 & 2 & 1 \\1 & 2 & 3 & 4 & 5 & 4 & 3 & 2 \\0 & 1 & 2 & 3 & 4 & 5 & 4 & 3 \\0 & 0 & 1 & 2 & 3 & 4 & 5 & 4 \\0 & 0 & 0 & 1 & 2 & 3 & 4 & 5\end{bmatrix}\begin{bmatrix}{F01} \\{F02} \\{F03} \\{F04} \\{F05} \\{F06} \\{F07} \\{F08}\end{bmatrix}} = {v \cdot \begin{bmatrix}{\sum\limits_{i = 08}^{12}{Ci}} \\{\sum\limits_{i = 07}^{11}{Ci}} \\{\sum\limits_{i = 06}^{10}{Ci}} \\{\sum\limits_{i = 05}^{09}{Ci}} \\{\sum\limits_{i = 04}^{08}{Ci}} \\{\sum\limits_{i = 03}^{07}{Ci}} \\{\sum\limits_{i = 02}^{06}{Ci}} \\{\sum\limits_{i = 01}^{05}{Ci}}\end{bmatrix}}} & (105)\end{matrix}$

[0593] When equation (105) is expressed by A·F=v·C, C, A, and v known,and F is unknown. A and v are known when the model is formed, while Cbecomes known when the pixel value is input in the addition processing.

[0594] By calculating the foreground components according to the normalequation based on the method of least squares, the error contained inthe pixel C can be distributed.

[0595] The equation generator 803 supplies the normal equation generatedas discussed above to the adder 804.

[0596] The adder 804 sets, based on the unit of processing supplied fromthe unit-of-processing determining portion 801, the pixel value Ccontained in the foreground component image in the matrix equationsupplied from the equation generator 803. The adder 804 supplies thematrix in which the pixel value C is set to a calculator 805.

[0597] The calculator 805 calculates the foreground component Fi/v fromwhich motion blur is eliminated by the processing based on a solution,such as a sweep-out method (Gauss-Jordan elimination), so as to obtainFi corresponding to i indicating one of the integers from 0 to 8, whichis the pixel value from which motion blur is eliminated. The calculator805 then outputs the foreground component image consisting of the pixelvalues Fi without motion blur, such as that in FIG. 61, to a motion-bluradder 806 and a selector 807.

[0598] In the foreground component image without motion blur shown inFIG. 61, the reason for setting F01 through F08 in C03 through C10,respectively, is not to change the position of the foreground componentimage with respect to the screen. However, F01 through F08 may be set inany desired positions.

[0599] The motion-blur adder 806 is able to adjust the amount of motionblur by adding the amount v′ by which motion blur is adjusted, which isdifferent from the amount of movement v, for example, the amount v′ bywhich motion blur is adjusted, which is one half the value of the amountof movement v, or the amount v′ by which motion blur is adjusted, whichis irrelevant to the amount of movement v. For example, as shown in FIG.62, the motion-blur adder 806 divides the foreground pixel value Fiwithout motion blur by the amount v′ by which motion blur is adjusted soas to obtain the foreground component Fi/v′. The motion-blur adder 806then calculates the sum of the foreground components Fi/v′, therebygenerating the pixel value in which the amount of motion blur isadjusted. For example, when the amount v′ by which motion blur isadjusted is 3, the pixel value C02 is set to (F01)/v′, the pixel valueC3 is set to (F01+F02)/v′, the pixel value C04 is set to(F01+F02+F03)/v′, and the pixel value C05 is set to (F02+F03+F04)/v′.

[0600] The motion-blur adder 806 supplies the foreground component imagein which the amount of motion blur is adjusted to a selector 807.

[0601] The selector 807 selects one of the foreground component imagewithout motion blur supplied from the calculator 805 and the foregroundcomponent image in which the amount of motion blur is adjusted suppliedfrom the motion-blur adder 806 based on a selection signal reflecting auser's selection, and outputs the selected foreground component image.

[0602] As discussed above, the motion-blur adjusting unit 106 is able toadjust the amount of motion blur based on the selection signal and theamount v′ by which motion blur is adjusted.

[0603] Also, for example, when the number of pixels corresponding to theunit of processing is 8, and the amount of movement v is 4, as shown inFIG. 63, the motion-blur adjusting unit 106 generates a matrix equationexpressed by equation (106). $\begin{matrix}{{\begin{bmatrix}4 & 3 & 2 & 1 & 0 \\3 & 4 & 3 & 2 & 1 \\2 & 3 & 4 & 3 & 2 \\1 & 2 & 3 & 4 & 3 \\0 & 1 & 2 & 3 & 4\end{bmatrix}\begin{bmatrix}{F01} \\{F02} \\{F03} \\{F04} \\{F05}\end{bmatrix}} = {v \cdot \begin{bmatrix}{\sum\limits_{i = 05}^{08}{Ci}} \\{\sum\limits_{i = 04}^{07}{Ci}} \\{\sum\limits_{i = 03}^{06}{Ci}} \\{\sum\limits_{i = 02}^{05}{Ci}} \\{\sum\limits_{i = 01}^{04}{Ci}}\end{bmatrix}}} & (106)\end{matrix}$

[0604] In this manner, the motion-blur adjusting unit 106 calculates Fi,which is the pixel value in which the amount of motion blur is adjusted,by setting up the equation in accordance with the length of the unit ofprocessing. Similarly, for example, when the number of pixels containedin the unit of processing is 100, the equation corresponding to 100pixels is generated so as to calculate Fi.

[0605]FIG. 64 illustrates an example of another configuration of themotion-blur adjusting unit 106. The same elements as those shown in FIG.58 are designated with like reference numerals, and an explanationthereof is thus omitted.

[0606] Based on a selection signal, a selector 821 directly supplies aninput motion vector and a positional signal thereof to theunit-of-processing determining portion 801 and the model-forming portion802. Alternatively, the selector 821 may substitute the magnitude of themotion vector by the amount v′ by which motion blur is adjusted, andthen supplies the motion vector and the positional signal thereof to theunit-of-processing determining portion 801 and the model-forming unit802.

[0607] With this arrangement, the unit-of-processing determining portion801 through the calculator 805 of the motion-blur adjusting unit 106shown in FIG. 64 are able to adjust the amount of motion blur inaccordance with the amount of movement v and the amount v′ by whichmotion blur is adjusted. For example, when the amount of movement v is5, and the amount v′ by which motion blur is adjusted is 3, theunit-of-processing determining portion 801 through the calculator 805 ofthe motion-blur adjusting unit 106 shown in FIG. 64 execute computationon the foreground component image in which the amount of movement v is 5shown in FIG. 60 according to the model shown in FIG. 62 in which theamount v′ by which motion blur is adjusted is 3. As a result, the imagecontaining motion blur having the amount of movement v of (amount ofmovement v)/(amount v′ by which motion blur is adjusted)=5/3, i.e.,about 1.7 is obtained. In this case, the calculated image does notcontain motion blur corresponding to the amount of movement v of 3.Accordingly, it should be noted that the relationship between the amountof movement v and the amount v′ by which motion blur is adjusted isdifferent from the result of the motion-blur adder 806.

[0608] As discussed above, the motion-blur adjusting unit 106 generatesthe equation in accordance with the amount of movement v and the unit ofprocessing, and sets the pixel values of the foreground component imagein the generated equation, thereby calculating the foreground componentimage in which the amount of motion blur is adjusted.

[0609] The processing for adjusting the amount of motion blur containedin the foreground component image executed by the motion-blur adjustingunit 106 is described below with reference to the flowchart of FIG. 65.

[0610] In step S801, the unit-of-processing determining portion 801 ofthe motion-blur adjusting unit 106 generates the unit of processingbased on the motion vector and the area information, and supplies thegenerated unit of processing to the model-forming portion 802.

[0611] In step S802, the model-forming portion 802 of the motion-bluradjusting unit 106 selects or generates the model in accordance with theamount of movement v and the unit of processing. In step S803, theequation generator 803 generates the normal equation based on theselected model.

[0612] In step S804, the adder 804 sets the pixel values of theforeground component image in the generated normal equation. In stepS805, the adder 804 determines whether the pixel values of all thepixels corresponding to the unit of processing are set. If it isdetermined that the pixel values of all the pixels corresponding to theunit of processing are not yet set, the process returns to step S804,and the processing for setting the pixel values in the normal equationis repeated.

[0613] If it is determined in step S805 that the pixel values of all thepixels corresponding to the unit of processing are set, the processproceeds to step S806. In step S806, the calculator 805 calculates thepixel values of the foreground in which the amount of motion blur isadjusted based on the normal equation in which the pixel values are setsupplied from the adder 804. The processing is then completed.

[0614] As discussed above, the motion-blur adjusting unit 106 is able toadjust the amount of motion blur of the foreground image containingmotion blur based on the motion vector and the area information.

[0615] That is, it is possible to adjust the amount of motion blurcontained in the pixel values, that is, contained in sampled data.

[0616]FIG. 66 is a block diagram illustrating another example of theconfiguration of the motion-blur adjusting unit 106. The motion vectorand the positional information thereof supplied from the motion detector102 are supplied to a unit-of-processing determining portion 901 and anadjusting portion 905. The area information supplied from the areaspecifying unit 104 is supplied to the unit-of-processing determiningportion 901. The foreground component image supplied from theforeground/background separator 105 is supplied to a calculator 904.

[0617] The unit-of-processing determining portion 901 generates the unitof processing based on the motion vector and the positional informationthereof, and the area information, and supplies the generated unit ofprocessing to a model-forming portion 902 together with the motionvector.

[0618] The model-forming portion 902 forms a model based on the motionvector and the input unit of processing. More specifically, for example,the model-forming portion 902 may store in advance a plurality of modelsin accordance with the number of pixels contained in the unit ofprocessing, the number of virtual divided portions of the pixel value inthe time direction, and the number of foreground components for eachpixel. The model-forming portion 902 may then select the model in whichthe correlation between the pixel values and the foreground componentsis designated, such as that in FIG. 67, based on the unit of processingand the number of virtual divided portions of the pixel value in thetime direction.

[0619] It is now assumed, for example, that the number of pixelscorresponding to the unit of processing is 12, and that the amount ofmovement v within the shutter time is 5. Then, the model-forming portion902 sets the number of virtual divided portions to 5, and selects amodel formed of eight types of foreground components so that theleftmost pixel contains one foreground component, the second pixel fromthe left contains two foreground components, the third pixel from theleft contains three foreground components, the fourth pixel from theleft contains four pixel components, the fifth pixel from the leftcontains five foreground components, the sixth pixel from the leftcontains five foreground components, the seventh pixel from the leftcontains five foreground components, the eighth pixel from the leftcontains five foreground components, the ninth pixel from the leftcontains four foreground components, the tenth pixel from the leftcontains three foreground components, the eleventh pixel from the leftcontains two foreground components, and the twelfth pixel from the leftcontains one foreground component.

[0620] Instead of selecting a model from the prestored models, themodel-forming portion 902 may generate a model based on the motionvector and the unit of processing when the motion vector and the unit ofprocessing are supplied.

[0621] An equation generator 903 generates an equation based on themodel supplied from the model-forming portion 902.

[0622] A description is now given, with reference to the models offoreground component images shown in FIGS. 67 through 69, of an exampleof the equation generated by the equation generator 903 when the numberof foreground components is 8, the number of pixels corresponding to theunit of processing is 12, and the amount of movement v is 5.

[0623] When the foreground components contained in the foregroundcomponent image corresponding to the shutter time/v are F01/v throughF08/v, the relationships between F01/v through F08/v and pixel valuesC01 through C12 can be expressed by equations (74) through (85), asstated above.

[0624] By considering the pixel values C12 and C11, the pixel value C12contains only the foreground component F08/v, as expressed by equation(107), and the pixel value C11 consists of the product sum of theforeground component F08/v and the foreground component F07/v.Accordingly, the foreground component F07/v can be found by equation(108).

F08/v=C12   (107)

F07/v=C11−C12   (108)

[0625] Similarly, by considering the foreground components contained inthe pixel values C10 through C01, the foreground components F06/vthrough F01/v can be found by equations (109) through (114),respectively.

F06/v=C10−C11   (109)

F05/v=C09−C10   (110)

F04/v=C08−C09   (111)

F03/v=C07−C08+C12   (112)

F02/v=C06−C07+C11−C12   (113)

F01/v=C05−C06+C10−C11   (114)

[0626] The equation generator 903 generates the equations forcalculating the foreground components by the difference between thepixel values, as indicated by the examples of equations (107) through(114). The equation generator 903 supplies the generated equations tothe calculator 904.

[0627] The calculator 904 sets the pixel values of the foregroundcomponent image in the equations supplied from the equation generator903 so as to obtain the foreground components based on the equations inwhich the pixel values are set. For example, when equations (107)through (114) are supplied from the equation generator 903, thecalculator 904 sets the pixel values C05 through C12 in equations (107)through (114).

[0628] The calculator 904 calculates the foreground components based onthe equations in which the pixel values are set. For example, thecalculator 904 calculates the foreground components F01/v through F08/v,as shown in FIG. 68, based on the calculations of equations (107)through (114) in which the pixel values C05 through C12 are set. Thecalculator 904 supplies the foreground components F01/v through F08/v tothe adjusting portion 905.

[0629] The adjusting portion 905 multiplies the foreground componentssupplied from the calculator 904 by the amount of movement v containedin the motion vector supplied from the unit-of-processing determiningportion 901 so as to obtain the foreground pixel values from whichmotion blur is eliminated. For example, when the foreground componentsF01/v through F08/v are supplied from the calculator 904, the adjustingportion 905 multiples each of the foreground components F01/v throughF08/v by the amount of movement v, i.e., 5, so as to obtain theforeground pixel values F01 through F08 from which motion blur iseliminated, as shown in FIG. 69.

[0630] The adjusting portion 905 supplies the foreground component imageconsisting of the foreground pixel values without motion blur calculatedas described above to a motion-blur adder 906 and a selector 907.

[0631] The motion-blur adder 906 is able to adjust the amount of motionblur by using the amount v′ by which motion blur is adjusted, which isdifferent from the amount of movement v, for example, the amount v′ bywhich motion blur is adjusted, which is one half the value of the amountof movement v, or the amount v′ by which motion blur is adjusted, whichis irrelevant to the amount of movement v. For example, as shown in FIG.62, the motion-blur adder 906 divides the foreground pixel value Fiwithout motion blur by the amount v′ by which motion blur is adjusted soas to obtain the foreground component Fi/v′. The motion-blur adder 906then calculates the sum of the foreground components Fi/v′, therebygenerating the pixel value in which the amount of motion blur isadjusted. For example, when the amount v′ by which motion blur isadjusted is 3, the pixel value C02 is set to (F01)/v′, the pixel valueC3 is set to (F01+F02)/v′, the pixel value C04 is set to(F01+F02+F03)/v′, and the pixel value C05 is set to (F02+F03+F04)/v′.

[0632] The motion-blur adder 906 supplies the foreground component imagein which the amount of motion blur is adjusted to the selector 907.

[0633] The selector 907 selects either the foreground component imagewithout motion blur supplied from the adjusting portion 905 or theforeground component image in which the amount of motion blur isadjusted supplied from the motion-blur adder 906 based on a selectionsignal reflecting a user's selection, and outputs the selectedforeground component image.

[0634] As discussed above, the motion-blur adjusting unit 106 is able toadjust the amount of motion blur based on the selection signal and theamount v′ by which motion blur is adjusted.

[0635] The processing for adjusting the amount of motion blur of theforeground executed by the motion-blur adjusting unit 106 configured asshown in FIG. 66 is described below with reference to the flowchart ofFIG. 70.

[0636] In step S901, the unit-of-processing determining portion 901 ofthe motion-blur adjusting unit 106 generates the unit of processingbased on the motion vector and the area information, and supplies thegenerated unit of processing to the model-forming portion 902 and theadjusting portion 905.

[0637] In step S902, the model-forming portion 902 of the motion-bluradjusting unit 106 selects or generates the model according to theamount of movement v and the unit of processing. In step S903, theequation generator 903 generates, based on the selected or generatedmodel, the equations for calculating the foreground components by thedifference between the pixel values of the foreground component image.

[0638] In step S904, the calculator 904 sets the pixel values of theforeground component image in the generated equations, and extracts theforeground components by using the difference between the pixel valuesbased on the equations in which the pixel values are set. In step S905,the calculator 904 determines whether all the foreground componentscorresponding to the unit of processing have been extracted. If it isdetermined that all the foreground components corresponding to the unitof processing have not been extracted, the process returns to step S904,and the processing for extracting the foreground components is repeated.

[0639] If it is determined in step S905 that all the foregroundcomponents corresponding to the unit of processing have been extracted,the process proceeds to step S906. In step S906, the adjusting portion905 adjusts each of the foreground components F01/v through F08/vsupplied from the calculator 904 based on the amount of movement v so asto obtain the foreground pixel values F01/v through F08/v from whichmotion blur is eliminated.

[0640] In step S907, the motion-blur adder 906 calculates the foregroundpixel values in which the amount of motion blur is adjusted, and theselector 907 selects the image without motion blur or the image in whichthe amount of motion blur is adjusted, and outputs the selected image.The processing is then completed.

[0641] As described above, the motion-blur adjusting unit 106 configuredas shown in FIG. 66 is able to more speedily adjust motion blur of theforeground image containing motion blur according to simplercomputations.

[0642] A known technique for partially eliminating motion blur, such asa Wiener filter, is effective when being used in the ideal state, but isnot sufficient for an actual image quantized and containing noise. Incontrast, it is proved that the motion-blur adjusting unit 106configured as shown in FIG. 66 is sufficiently effective for an actualimage quantized and containing noise. It is thus possible to eliminatemotion blur with high precision.

[0643] As described above, the image processing apparatus configured asshown in FIG. 2 is able to adjust the amount of motion blur contained inan input image.

[0644] The embodiment has been discussed above by setting the mixtureratio α to the ratio of the background components contained in the pixelvalues. However, the mixture ratio α may be set to the ratio of theforeground components contained in the pixel values.

[0645] The embodiment has been discussed above by setting the movingdirection of the foreground object to the direction from the left to theright. However, the moving direction is not restricted to theabove-described direction.

[0646] In the above description, a real-space image having athree-dimensional space and time axis information is projected onto atime space having a two-dimensional space and time axis information byusing a video camera. However, the present invention is not restrictedto this example, and can be applied to the following case. When agreater amount of first information in one-dimensional space isprojected onto a smaller amount of second information in atwo-dimensional space, distortion generated by the projection can becorrected, significant information can be extracted, or a more naturalimage can be synthesized.

[0647] The sensor is not restricted to a CCD, and may be another type ofsensor, such as a solid-state image-capturing device, for example, a BBD(Bucket Brigade Device), a CID (Charge Injection Device), or a CPD(Charge Priming Device), or a CMOS (Complementary Metal OxideSemiconductor). Also, the sensor does not have to be a sensor in whichdetection devices are arranged in a matrix, and may be a sensor in whichdetection devices are arranged in one line.

[0648] A recording medium in which a program for performing the signalprocessing of the present invention is recorded may be formed of apackage medium in which the program is recorded, which is distributedfor providing the program to a user separately from the computer, asshown in FIG. 1, such as the magnetic disk 51 (including a floppy(registered trade name) disk), the optical disc 52 (including a CD-ROM(Compact Disc-Read Only Memory) and a DVD (Digital Versatile Disc)), themagneto-optical disk 53 (including MD (Mini-Disk) (registered tradename)), or the semiconductor memory 54. The recording medium may also beformed of the ROM 22 or a hard disk contained in the storage unit 28 inwhich the program is recorded, such a recording medium being provided tothe user while being prestored in the computer.

[0649] The steps forming the program recorded in a recording medium maybe executed chronologically according to the orders described in thespecification. However, they do not have to be executed in a time-seriesmanner, and they may be executed concurrently or individually.

[0650] Industrial Applicability

[0651] According to the present invention, it is possible to specify abackground image area, a moving object image area, and an image area inwhich the mixture of the background image area and the moving objectimage area occurs.

1. An image processing apparatus for processing image data which isformed of a predetermined number of pixel data obtained by animage-capturing device including a predetermined number of pixels, thepixels having a time integrating function, said image processingapparatus comprising: relational-expression generating means forextracting, in correspondence with a designated pixel of a designatedframe of the image data, the pixel data of a peripheral frame around thedesignated frame as background pixel data corresponding to a backgroundobject which forms a background among a plurality of objects of theimage data, and also for extracting designated pixel data of thedesignated pixel contained in the designated frame so as to generate aplurality of relational expressions concerning the designated pixelindicating a relationship between the designated pixel data and thebackground pixel data; mixture-ratio detection means for detecting amixture ratio indicating a mixture state of the plurality of objects inthe real world concerning the designated pixel based on the relationalexpressions; predictive-error calculation means for calculating apredictive error by substituting the mixture ratio detected by saidmixture-ratio detection means into the relational expressions; coveredbackground area/uncovered background area specifying means forspecifying, based on the predictive error, whether an area to which thedesignated pixel belongs is a mixed area in which the plurality ofobjects are mixed and is also a covered background area formed at aleading end in a moving direction of a foreground object which forms aforeground among the plurality of objects, or is the mixed area and isalso an uncovered background area formed at a trailing end in the movingdirection of the foreground object; and foreground area/background areaspecifying means for specifying whether the area to which the designatedpixel belongs is a foreground area consisting of only foreground objectcomponents which form the foreground object or a background areaconsisting of only background object components which form thebackground object.
 2. An image processing apparatus according to claim1, wherein: said mixture-ratio detection means detects the foregroundobject components contained in the designated pixel in correspondencewith the designated pixel based on the relational expressions, and alsodetects the mixture ratio; and said predictive-error calculation meanscalculates the predictive error by substituting the mixture ratio andthe foreground object components contained in the designated pixeldetected by said mixture-ratio detection means into the relationalexpressions.
 3. An image processing apparatus according to claim 2,wherein said relational-expression generating means extracts the pixeldata of the peripheral frame corresponding to the designated pixel asthe background pixel data corresponding to the background object, andalso extracts the designated pixel data of the designated pixel andvicinity pixel data of a vicinity pixel positioned in the vicinity ofthe designated pixel in the designated frame, and generates theplurality of relational expressions concerning the designated pixelindicating a relationship among the designated pixel data, the vicinitypixel data, and the background pixel data corresponding to thedesignated pixel data or the vicinity pixel data.
 4. An image processingapparatus according to claim 3, wherein said relational-expressiongenerating means generates the plurality of relational expressions basedon a first approximation in which the foreground object componentscontained in the designated pixel data and the vicinity pixel data areequal, and a second approximation in which the mixture ratio in themixed area linearly changes with respect to a position of a pixel of themixed area.
 5. An image processing apparatus according to claim 3,wherein said relational-expression generating means generates theplurality of relational expressions based on a first approximation inwhich the foreground object components contained in the designated pixeldata and the vicinity pixel data are equal, and a second approximationin which the mixture ratio in the mixed area planarly changes withrespect to a position of a pixel of the mixed area.
 6. An imageprocessing apparatus according to claim 3, wherein said mixture-ratiodetection means detects the mixture ratio by solving the plurality ofrelational expressions according to a method of least squares.
 7. Animage processing apparatus according to claim 3, wherein saidrelational-expression generating means generates the plurality ofrelational expressions by extracting the pixel data of a frame prior tothe designated frame as the background pixel data when the designatedpixel belongs to the covered background area and by extracting the pixeldata of a frame subsequent to the designated frame as the backgroundpixel data when the designated pixel belongs to the uncovered backgroundarea.
 8. An image processing apparatus according to claim 2, whereinsaid relational-expression generating means generates the plurality ofrelational expressions by extracting, in correspondence with thedesignated pixel, mixed pixel data indicating a mixture state in whichthe plurality of objects are mixed from the designated frame and theperipheral frame based on a motion of the foreground object and by alsoextracting, in correspondence with each item of the mixed pixel data,the background pixel data corresponding to the background object from aframe different from the frame from which the mixed pixel data isextracted based on a motion of the background object.
 9. An imageprocessing apparatus according to claim 8, wherein saidrelational-expression generating means generates the plurality ofrelational expressions based on a first approximation in which theforeground object components corresponding to the mixed pixel data areequal and a second approximation in which the mixed pixel data extractedfrom the designated frame and the peripheral frame are uniform.
 10. Animage processing apparatus according to claim 8, wherein: saidrelational-expression generating means generates the plurality ofrelational expressions by extracting, in correspondence with thedesignated pixel, the mixed pixel data indicating the mixture state inwhich the plurality of objects are mixed from the designated frame andthe peripheral frame based on the motion of the foreground object and byalso extracting, in correspondence with each item of the mixed pixeldata, the background pixel data corresponding to the background objectfrom a frame prior to the frame from which the mixed pixel data isextracted based on the motion of the background object; and said coveredbackground area/uncovered background area specifying means specifies anarea in which the predictive error is greater than or equal to apredetermined threshold as the uncovered background area.
 11. An imageprocessing apparatus according to claim 8, wherein: saidrelational-expression generating means generates the plurality ofrelational expressions by extracting, in correspondence with thedesignated pixel, the mixed pixel data indicating the mixture state inwhich the plurality of objects are mixed from the designated frame andthe peripheral frame based on the motion of the foreground object andalso by extracting, in correspondence with each item of the mixed pixeldata, the background pixel data corresponding to the background objectfrom a frame subsequent to the frame from which the mixed pixel data isextracted based on the motion of the background object; and said coveredbackground area/uncovered background area specifying means specifies anarea in which the predictive error is greater than or equal to apredetermined threshold as the covered background area.
 12. An imageprocessing method for processing image data which is formed of apredetermined number of pixel data obtained by an image-capturing deviceincluding a predetermined number of pixels, the pixels having a timeintegrating function, said image processing method comprising: arelational-expression generating step of extracting, in correspondencewith a designated pixel of a designated frame of the image data, thepixel data of a peripheral frame around the designated frame asbackground pixel data corresponding to a background object which forms abackground among a plurality of objects of the image data, and also ofextracting designated pixel data of the designated pixel contained inthe designated frame so as to generate a plurality of relationalexpressions concerning the designated pixel indicating a relationshipbetween the designated pixel data and the background pixel data; amixture-ratio detection step of detecting a mixture ratio indicating amixture state of the plurality of objects in the real world concerningthe designated pixel based on the relational expressions; apredictive-error calculation step of calculating a predictive error bysubstituting the mixture ratio detected by processing in saidmixture-ratio detection step into the relational expressions; a coveredbackground area/uncovered background area specifying step of specifying,based on the predictive error, whether an area to which the designatedpixel belongs is a mixed area in which the plurality of objects aremixed and is also a covered background area formed at a leading end in amoving direction of a foreground object which forms a foreground amongthe plurality of objects, or is the mixed area and is also an uncoveredbackground area formed at a trailing end in the moving direction of theforeground object; and a foreground area/background area specifying stepof specifying whether the area to which the designated pixel belongs isa foreground area consisting of only foreground object components whichform the foreground object or a background area consisting of onlybackground object components which form the background object.
 13. Animage processing method according to claim 12, wherein: in saidmixture-ratio detection step, the foreground object components containedin the designated pixel is detected in correspondence with thedesignated pixel based on the relational expressions, and the mixtureratio is also detected; and in said predictive-error calculation step,the predictive error is calculated by substituting the mixture ratio andthe foreground object components contained in the designated pixeldetected by processing in said mixture-ratio detection step into therelational expressions.
 14. An image processing method according toclaim 13, wherein, in said relational-expression generating step, thepixel data of the peripheral frame corresponding to the designated pixelis extracted as the background pixel data corresponding to thebackground object, and the designated pixel data of the designated pixeland vicinity pixel data of a vicinity pixel positioned in the vicinityof the designated pixel in the designated frame are also extracted, andthe plurality of relational expressions concerning the designated pixelindicating a relationship among the designated pixel data, the vicinitypixel data, and the background pixel data corresponding to thedesignated pixel data or the vicinity pixel data.
 15. An imageprocessing method according to claim 14, wherein, in saidrelational-expression generating step, the plurality of relationalexpressions are generated based on a first approximation in which theforeground object components contained in the designated pixel data andthe vicinity pixel data are equal, and a second approximation in whichthe mixture ratio in the mixed area linearly changes with respect to aposition of a pixel of the mixed area.
 16. An image processing methodaccording to claim 14, wherein, in said relational-expression generatingstep, the plurality of relational expressions are generated based on afirst approximation in which the foreground object components containedin the designated pixel data and the vicinity pixel data are equal, anda second approximation in which the mixture ratio in the mixed areaplanarly changes with respect to a position of a pixel of the mixedarea.
 17. An image processing method according to claim 14, wherein, insaid mixture-ratio detection step, the mixture ratio is detected bysolving the plurality of relational expressions according to a method ofleast squares.
 18. An image processing method according to claim 14,wherein, in said relational-expression generating step, the plurality ofrelational expressions are generated by extracting the pixel data of aframe prior to the designated frame as the background pixel data whenthe designated pixel belongs to the covered background area and byextracting the pixel data of a frame subsequent to the designated frameas the background pixel data when the designated pixel belongs to theuncovered background area.
 19. An image processing method according toclaim 13, wherein, in said relational-expression generating step, theplurality of relational expressions are generated by extracting, incorrespondence with the designated pixel, mixed pixel data indicating amixture state in which the plurality of objects are mixed from thedesignated frame and the peripheral frame based on a motion of theforeground object and by also extracting, in correspondence with eachitem of the mixed pixel data, the background pixel data corresponding tothe background object from a frame different from the frame from whichthe mixed pixel data is extracted based on a motion of the backgroundobject.
 20. An image processing method according to claim 19, wherein,in said relational-expression generating step, the plurality ofrelational expressions are generated based on a first approximation inwhich the foreground object components corresponding to the mixed pixeldata are equal and a second approximation in which the mixed pixel dataextracted from the designated frame and the peripheral frame areuniform.
 21. An image processing method according to claim 19, wherein:in said relational-expression generating step, the plurality ofrelational expressions are generated by extracting, in correspondencewith the designated pixel, the mixed pixel data indicating the mixturestate in which the plurality of objects are mixed from the designatedframe and the peripheral frame based on the motion of the foregroundobject and by also extracting, in correspondence with each item of themixed pixel data, the background pixel data corresponding to thebackground object from a frame prior to the frame from which the mixedpixel data is extracted based on the motion of the background object;and in said covered background area/uncovered background area specifyingstep, an area in which the predictive error is greater than or equal toa predetermined threshold is specified as the uncovered background area.22. An image processing method according to claim 19, wherein: in saidrelational-expression generating step, the plurality of relationalexpressions are generated by extracting, in correspondence with thedesignated pixel, the mixed pixel data indicating the mixture state inwhich the plurality of objects are mixed from the designated frame andthe peripheral frame based on the motion of the foreground object andalso by extracting, in correspondence with each item of the mixed pixeldata, the background pixel data corresponding to the background objectfrom a frame subsequent to the frame from which the mixed pixel data isextracted based on the motion of the background object; and in saidcovered background area/uncovered background area specifying step, anarea in which the predictive error is greater than or equal to apredetermined threshold is specified as the covered background area. 23.A recording medium in which a computer-readable program is recorded,said computer-readable program being used for processing image datawhich is formed of a predetermined number of pixel data obtained by animage-capturing device including a predetermined number of pixels, thepixels having a time integrating function, said computer-readableprogram comprising: a relational-expression generating step ofextracting, in correspondence with a designated pixel of a designatedframe of the image data, the pixel data of a peripheral frame around thedesignated frame as background pixel data corresponding to a backgroundobject which forms a background among a plurality of objects of theimage data, and also of extracting designated pixel data of thedesignated pixel contained in the designated frame so as to generate aplurality of relational expressions concerning the designated pixelindicating a relationship between the designated pixel data and thebackground pixel data; a mixture-ratio detection step of detecting amixture ratio indicating a mixture state of the plurality of objects inthe real world concerning the designated pixel based on the relationalexpressions; a predictive-error calculation step of calculating apredictive error by substituting the mixture ratio detected byprocessing in said mixture-ratio detection step into the relationalexpressions; a covered background area/uncovered background areaspecifying step of specifying, based on the predictive error, whether anarea to which the designated pixel belongs is a mixed area in which theplurality of objects are mixed and is also a covered background areaformed at a leading end in a moving direction of a foreground objectwhich forms a foreground among the plurality of objects, or is the mixedarea and is also an uncovered background area formed at a trailing endin the moving direction of the foreground object; and a foregroundarea/background area specifying step of specifying whether the area towhich the designated pixel belongs is a foreground area consisting ofonly foreground object components which form the foreground object or abackground area consisting of only background object components whichform the background object.
 24. A recording medium according to claim23, wherein: in said mixture-ratio detection step, the foreground objectcomponents contained in the designated pixel is detected incorrespondence with the designated pixel based on the relationalexpressions, and the mixture ratio is also detected; and in saidpredictive-error calculation step, the predictive error is calculated bysubstituting the mixture ratio and the foreground object componentscontained in the designated pixel detected by processing in saidmixture-ratio detection step into the relational expressions.
 25. Arecording medium according to claim 24, wherein, in saidrelational-expression generating step, the pixel data of the peripheralframe corresponding to the designated pixel is extracted as thebackground pixel data corresponding to the background object, and thedesignated pixel data of the designated pixel and vicinity pixel data ofa vicinity pixel positioned in the vicinity of the designated pixel inthe designated frame are also extracted, and the plurality of relationalexpressions concerning the designated pixel indicating a relationshipamong the designated pixel data, the vicinity pixel data, and thebackground pixel data corresponding to the designated pixel data or thevicinity pixel data.
 26. A recording medium according to claim 25,wherein, in said relational-expression generating step, the plurality ofrelational expressions are generated based on a first approximation inwhich the foreground object components contained in the designated pixeldata and the vicinity pixel data are equal, and a second approximationin which the mixture ratio in the mixed area linearly changes withrespect to a position of a pixel of the mixed area.
 27. A recordingmedium according to claim 25, wherein, in said relational-expressiongenerating step, the plurality of relational expressions are generatedbased on a first approximation in which the foreground object componentscontained in the designated pixel data and the vicinity pixel data areequal, and a second approximation in which the mixture ratio in themixed area planarly changes with respect to a position of a pixel of themixed area.
 28. A recording medium according to claim 25, wherein, insaid mixture-ratio detection step, the mixture ratio is detected bysolving the plurality of relational expressions according to a method ofleast squares.
 29. A recording medium according to claim 25, wherein, insaid relational-expression generating step, the plurality of relationalexpressions are generated by extracting the pixel data of a frame priorto the designated frame as the background pixel data when the designatedpixel belongs to the covered background area and by extracting the pixeldata of a frame subsequent to the designated frame as the backgroundpixel data when the designated pixel belongs to the uncovered backgroundarea.
 30. A recording medium according to claim 24, wherein, in saidrelational-expression generating step, the plurality of relationalexpressions are generated by extracting, in correspondence with thedesignated pixel, mixed pixel data indicating a mixture state in whichthe plurality of objects are mixed from the designated frame and theperipheral frame based on a motion of the foreground object and by alsoextracting, in correspondence with each item of the mixed pixel data,the background pixel data corresponding to the background object from aframe different from the frame from which the mixed pixel data isextracted based on a motion of the background object.
 31. A recordingmedium according to claim 30, wherein, in said relational-expressiongenerating step, the plurality of relational expressions are generatedbased on a first approximation in which the foreground object componentscorresponding to the mixed pixel data are equal and a secondapproximation in which the mixed pixel data extracted from thedesignated frame and the peripheral frame are uniform.
 32. A recordingmedium according to claim 30, wherein: in said relational-expressiongenerating step, the plurality of relational expressions are generatedby extracting, in correspondence with the designated pixel, the mixedpixel data indicating the mixture state in which the plurality ofobjects are mixed from the designated frame and the peripheral framebased on the motion of the foreground object and by also extracting, incorrespondence with each item of the mixed pixel data, the backgroundpixel data corresponding to the background object from a frame prior tothe frame from which the mixed pixel data is extracted based on themotion of the background object; and in said covered backgroundarea/uncovered background area specifying step, an area in which thepredictive error is greater than or equal to a predetermined thresholdis specified as the uncovered background area.
 33. A recording mediumaccording to claim 30, wherein: in said relational-expression generatingstep, the plurality of relational expressions are generated byextracting, in correspondence with the designated pixel, the mixed pixeldata indicating the mixture state in which the plurality of objects aremixed from the designated frame and the peripheral frame based on themotion of the foreground object and also by extracting, incorrespondence with each item of the mixed pixel data, the backgroundpixel data corresponding to the background object from a framesubsequent to the frame from which the mixed pixel data is extractedbased on the motion of the background object; and in said coveredbackground area/uncovered background area specifying step, an area inwhich the predictive error is greater than or equal to a predeterminedthreshold is specified as the covered background area.
 34. A program forallowing a computer for processing image data formed of a predeterminednumber of pixel data obtained by an image-capturing device including apredetermined number of pixels, the pixels having a time integratingfunction, to execute: a relational-expression generating step ofextracting, in correspondence with a designated pixel of a designatedframe of the image data, the pixel data of a peripheral frame around thedesignated frame as background pixel data corresponding to a backgroundobject which forms a background among a plurality of objects of theimage data, and also of extracting designated pixel data of thedesignated pixel contained in the designated frame so as to generate aplurality of relational expressions concerning the designated pixelindicating a relationship between the designated pixel data and thebackground pixel data; a mixture-ratio detection step of detecting amixture ratio indicating a mixture state of the plurality of objects inthe real world concerning the designated pixel based on the relationalexpressions; a predictive-error calculation step of calculating apredictive error by substituting the mixture ratio detected byprocessing in said mixture-ratio detection step into the relationalexpressions; a covered background area/uncovered background areaspecifying step of specifying, based on the predictive error, whether anarea to which the designated pixel belongs is a mixed area in which theplurality of objects are mixed and is also a covered background areaformed at a leading end in a moving direction of a foreground objectwhich forms a foreground among the plurality of objects, or is the mixedarea and is also an uncovered background area formed at a trailing endin the moving direction of the foreground object; and a foregroundarea/background area specifying step of specifying whether the area towhich the designated pixel belongs is a foreground area consisting ofonly foreground object components which form the foreground object or abackground area consisting of only background object components whichform the background object.
 35. A program according to claim 34,wherein: in said mixture-ratio detection step, the foreground objectcomponents contained in the designated pixel is detected incorrespondence with the designated pixel based on the relationalexpressions, and the mixture ratio is also detected; and in saidpredictive-error calculation step, the predictive error is calculated bysubstituting the mixture ratio and the foreground object componentscontained in the designated pixel detected by processing in saidmixture-ratio detection step into the relational expressions.
 36. Aprogram according to claim 35, wherein, in said relational-expressiongenerating step, the pixel data of the peripheral frame corresponding tothe designated pixel is extracted as the background pixel datacorresponding to the background object, and the designated pixel data ofthe designated pixel and vicinity pixel data of a vicinity pixelpositioned in the vicinity of the designated pixel in the designatedframe are also extracted, and the plurality of relational expressionsconcerning the designated pixel indicating a relationship among thedesignated pixel data, the vicinity pixel data, and the background pixeldata corresponding to the designated pixel data or the vicinity pixeldata.
 37. A program according to claim 36, wherein, in saidrelational-expression generating step, the plurality of relationalexpressions are generated based on a first approximation in which theforeground object components contained in the designated pixel data andthe vicinity pixel data are equal, and a second approximation in whichthe mixture ratio in the mixed area linearly changes with respect to aposition of a pixel of the mixed area.
 38. A program according to claim36, wherein, in said relational-expression generating step, theplurality of relational expressions are generated based on a firstapproximation in which the foreground object components contained in thedesignated pixel data and the vicinity pixel data are equal, and asecond approximation in which the mixture ratio in the mixed areaplanarly changes with respect to a position of a pixel of the mixedarea.
 39. A program according to claim 36, wherein, in saidmixture-ratio detection step, the mixture ratio is detected by solvingthe plurality of relational expressions according to a method of leastsquares.
 40. A program according to claim 36, wherein, in saidrelational-expression generating step, the plurality of relationalexpressions are generated by extracting the pixel data of a frame priorto the designated frame as the background pixel data when the designatedpixel belongs to the covered background area and by extracting the pixeldata of a frame subsequent to the designated frame as the backgroundpixel data when the designated pixel belongs to the uncovered backgroundarea.
 41. A program according to claim 35, wherein, in saidrelational-expression generating step, the plurality of relationalexpressions are generated by extracting, in correspondence with thedesignated pixel, mixed pixel data indicating a mixture state in whichthe plurality of objects are mixed from the designated frame and theperipheral frame based on a motion of the foreground object and by alsoextracting, in correspondence with each item of the mixed pixel data,the background pixel data corresponding to the background object from aframe different from the frame from which the mixed pixel data isextracted based on a motion of the background object.
 42. A programaccording to claim 41, wherein, in said relational-expression generatingstep, the plurality of relational expressions are generated based on afirst approximation in which the foreground object componentscorresponding to the mixed pixel data are equal and a secondapproximation in which the mixed pixel data extracted from thedesignated frame and the peripheral frame are uniform.
 43. A programaccording to claim 41, wherein: in said relational-expression generatingstep, the plurality of relational expressions are generated byextracting, in correspondence with the designated pixel, the mixed pixeldata indicating the mixture state in which the plurality of objects aremixed from the designated frame and the peripheral frame based on themotion of the foreground object and by also extracting, incorrespondence with each item of the mixed pixel data, the backgroundpixel data corresponding to the background object from a frame prior tothe frame from which the mixed pixel data is extracted based on themotion of the background object; and in said covered backgroundarea/uncovered background area specifying step, an area in which thepredictive error is greater than or equal to a predetermined thresholdis specified as the uncovered background area.
 44. A program accordingto claim 41, wherein: in said relational-expression generating step, theplurality of relational expressions are generated by extracting, incorrespondence with the designated pixel, the mixed pixel dataindicating the mixture state in which the plurality of objects are mixedfrom the designated frame and the peripheral frame based on the motionof the foreground object and also by extracting, in correspondence witheach item of the mixed pixel data, the background pixel datacorresponding to the background object from a frame subsequent to theframe from which the mixed pixel data is extracted based on the motionof the background object; and in said covered background area/uncoveredbackground area specifying step, an area in which the predictive erroris greater than or equal to a predetermined threshold is specified asthe covered background area.
 45. An image-capturing apparatuscomprising: image-capturing means for outputting a subject imagecaptured by an image-capturing device including a predetermined numberof pixels, the pixels having a time integrating function, as image dataformed of a predetermined number of pixel data; relational-expressiongenerating means for extracting, in correspondence with a designatedpixel of a designated frame of the image data, the pixel data of aperipheral frame around the designated frame as background pixel datacorresponding to a background object which forms a background among aplurality of objects of the image data, and also for extractingdesignated pixel data of the designated pixel contained in thedesignated frame so as to generate a plurality of relational expressionsconcerning the designated pixel indicating a relationship between thedesignated pixel data and the background pixel data; mixture-ratiodetection means for detecting a mixture ratio indicating a mixture stateof the plurality of objects in the real world concerning the designatedpixel based on the relational expressions; predictive-error calculationmeans for calculating a predictive error by substituting the mixtureratio detected by said mixture-ratio detection means into the relationalexpressions; covered background area/uncovered background areaspecifying means for specifying, based on the predictive error, whetheran area to which the designated pixel belongs is a mixed area in whichthe plurality of objects are mixed and is also a covered background areaformed at a leading end in a moving direction of a foreground objectwhich forms a foreground among the plurality of objects, or is the mixedarea and is also an uncovered background area formed at a trailing endin the moving direction of the foreground object; and foregroundarea/background area specifying means for specifying whether the area towhich the designated pixel belongs is a foreground area consisting ofonly foreground object components which form the foreground object or abackground area consisting of only background object components whichform the background object.
 46. An image-capturing apparatus accordingto claim 45, wherein: said mixture-ratio detection means detects theforeground object components contained in the designated pixel incorrespondence with the designated pixel based on the relationalexpressions, and also detects the mixture ratio; and saidpredictive-error calculation means calculates the predictive error bysubstituting the mixture ratio and the foreground object componentscontained in the designated pixel detected by said mixture-ratiodetection means into the relational expressions.
 47. An image-capturingapparatus according to claim 46, wherein said relational-expressiongenerating means extracts the pixel data of the peripheral framecorresponding to the designated pixel as the background pixel datacorresponding to the background object, and also extracts the designatedpixel data of the designated pixel and vicinity pixel data of a vicinitypixel positioned in the vicinity of the designated pixel in thedesignated frame, and generates the plurality of relational expressionsconcerning the designated pixel indicating a relationship among thedesignated pixel data, the vicinity pixel data, and the background pixeldata corresponding to the designated pixel data or the vicinity pixeldata.
 48. An image-capturing apparatus according to claim 47, whereinsaid relational-expression generating means generates the plurality ofrelational expressions based on a first approximation in which theforeground object components contained in the designated pixel data andthe vicinity pixel data are equal, and a second approximation in whichthe mixture ratio in the mixed area linearly changes with respect to aposition of a pixel of the mixed area.
 49. An image-capturing apparatusaccording to claim 47, wherein said relational-expression generatingmeans generates the plurality of relational expressions based on a firstapproximation in which the foreground object components contained in thedesignated pixel data and the vicinity pixel data are equal, and asecond approximation in which the mixture ratio in the mixed areaplanarly changes with respect to a position of a pixel of the mixedarea.
 50. An image-capturing apparatus according to claim 47, whereinsaid mixture-ratio detection means detects the mixture ratio by solvingthe plurality of relational expressions according to a method of leastsquares.
 51. An image-capturing apparatus according to claim 47, whereinsaid relational-expression generating means generates the plurality ofrelational expressions by extracting the pixel data of a frame prior tothe designated frame as the background pixel data when the designatedpixel belongs to the covered background area and by extracting the pixeldata of a frame subsequent to the designated frame as the backgroundpixel data when the designated pixel belongs to the uncovered backgroundarea.
 52. An image-capturing apparatus according to claim 46, whereinsaid relational-expression generating means generates the plurality ofrelational expressions by extracting, in correspondence with thedesignated pixel, mixed pixel data indicating a mixture state in whichthe plurality of objects are mixed from the designated frame and theperipheral frame based on a motion of the foreground object and by alsoextracting, in correspondence with each item of the mixed pixel data,the background pixel data corresponding to the background object from aframe different from the frame from which the mixed pixel data isextracted based on a motion of the background object.
 53. Animage-capturing apparatus according to claim 52, wherein saidrelational-expression generating means generates the plurality ofrelational expressions based on a first approximation in which theforeground object components corresponding to the mixed pixel data areequal and a second approximation in which the mixed pixel data extractedfrom the designated frame and the peripheral frame are uniform.
 54. Animage-capturing apparatus according to claim 52, wherein: saidrelational-expression generating means generates the plurality ofrelational expressions by extracting, in correspondence with thedesignated pixel, the mixed pixel data indicating the mixture state inwhich the plurality of objects are mixed from the designated frame andthe peripheral frame based on the motion of the foreground object and byalso extracting, in correspondence with each item of the mixed pixeldata, the background pixel data corresponding to the background objectfrom a frame prior to the frame from which the mixed pixel data isextracted based on the motion of the background object; and said coveredbackground area/uncovered background area specifying means specifies anarea in which the predictive error is greater than or equal to apredetermined threshold as the uncovered background area.
 55. Animage-capturing apparatus according to claim 52, wherein: saidrelational-expression generating means generates the plurality ofrelational expressions by extracting, in correspondence with thedesignated pixel, the mixed pixel data indicating the mixture state inwhich the plurality of objects are mixed from the designated frame andthe peripheral frame based on the motion of the foreground object andalso by extracting, in correspondence with each item of the mixed pixeldata, the background pixel data corresponding to the background objectfrom a frame subsequent to the frame from which the mixed pixel data isextracted based on the motion of the background object; and said coveredbackground area/uncovered background area specifying means specifies anarea in which the predictive error is greater than or equal to apredetermined threshold as the covered background area.